* Add v8 upgrade document and fix some tiny doc issues.

* Add link to STAM paper.

Here are the list of changes we made in this pull request. Top 3 are the principle changes, others are following these principles.
1. New agent and mesh report protocol. 
2. New agent header protocol. 
3. Service register, instance register and network address register have been removed permanently.
4. Service traffic, instance traffic and network alias metrics are added to replace the service, instance and network address inventory.
5. Register process has been removed.
6. Metrics stream process supports insert only mode, especially for traffic entities.
7. Metrics stream process supports no-downsampling mode for traffic entities and network alias.
8. Remove all register mechanism and cache in the java agent.
9. Remove MONTH step in GraphQL query.
10. Update UI to remove MONTH step query, the max query range is 60 days now.
11. Simplify the TTL to metrics and record. And the unit has been formatted in Day unit. No specific TTL for ElasticSearch storage.
12. Buffer mechanism of trace receiver and mesh receiver has been removed due to no register.
13. New service id, instance id and endpoint id rules, including service relation, instance relation and endpoint relation id rules.
14. Java agent support `keep tracing` mode, meaning, agent generating tracing context even the backend is unconnected/unavailable.
15. Plugin test tool up to date, in order to support new protocol.
16. Plugin tests expected data files updated.
17. E2E tests updated.
18. Telemetry of Grafana config has been merged into one.
19. Documentation updates.
20. [TBD] InfluxDB storage implementation is not available, need @dmsolr to fix later, in order to reduce the master change block by this PR.

* Finish step one, source and entity changed.

* Step 2, finish the basic and core DAO changes.

* Step 3. Change all source codes of backend, and make project compiling successfully.

* Make startup successful and persistence works.

* Fix dead codes in the MySQLTableInstaller.

* Fix mischange.

* Fix MySQL storage bootstrap error.

* Rollback dependency change.

* Simply enable tailing logs from container no mater it's in CI or not

* Fix segment table issue.

* Fix MySQL Instanller.

* Support Influxdb implementation of new endpoint traffic.

* Set and modify timeout to 90mins

* Remove unnecessary entity in the EndpointTraffic.

* Fix wrong entity builder and make name more clear.

* Fix 2 equal methods bug.

* Fix InfluxDB identifier(name) conflict issue.

* Fix endpoint topology query, endpoint id should be changed as a string.

* Fix a missing change.

* Fix a wrong commit.

* Column name can't be changed, due to it affect the hybrid metadb(h2/mysql) query, change it explicitly with double quotation marks.

* Fix formats.

* Remove endpoint/operation register from the agent. and change the plugin tests(without local tests). operationId relation codes have been removed from agent too.

* Try to fix the hytrix case.

* Fix 3 cases.

* Try to fix cases.

* Fix 2.

* Fix one.

* Fix the serviceId type mis-change.

* Fix int query

* Fix hystrix case.

* Fix a case.

* Fix EndpointCallRelationDispatcher set the source/dest endpoint without id encoding.

* Update documentation and add 2 test cases.
Co-authored-by: Nkezhenxu94 <kezhenxu94@163.com>

* provide the data transmission protocol
Co-authored-by: NMrproliu <mrproliu@lagou.com>
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>
Co-authored-by: Nkezhenxu94 <kezhenxu94@163.com>
Co-authored-by: Nzhang-wei <pknfe@outlook.com>

* Drop support of protocol v1 (sw3)

* Remove versioning logic further

* Remove more version5-only classes

* Commit missing files

* Update submodule and address review comment

* Fix failed tests

* Support new percentile func with new alarm and exporter for this new func.

* Fix e2e and OAL script

* Fix wrong column.

* Fix percentile bug and oal engine bug.

* Update query protocol and add percentile test case

* Support new query

* Adopt GraphQL requirement

* Fix wrong type cast.

* Fix query in H2 and ES.

* Fix docs and comments.

* Fix an e2e compile issue

* Fix javadoc issue and e2e test issue.

* Change CPM to Apdex in TTL test.

* Fix OAL for TTL e2e

* Add metrics query for service percentile.

* Fix OAL engine bug. Method deserialize is not working when more than two field types are IntKeyLongValueHashMap

* Support multiple IntKeyLongValueHashMap fields in remote. About serialize/deserialize methods.

* Fix graphql statement error in e2e.

* Fix serialize not working and add generated serialize/deserialize of percentile into test cases.

* Fix test case format

* Remove generated code test.

* Fix failed e2e test

* Use avg resp time to apdex in the TTL test.

* ADD multiple linear metrics check for endpoint in e2e cluster.

* Support `-` to represent no threshold and doc of alarm about this.

* Move break to right place.

* Fix wrong break(s)

* Fix break and add a test case for multiple values alarm.

* Fix format.

* Add more doc for this new feature and GraphQL query protocol.
Co-authored-by: NJared Tan <jian.tan@daocloud.io>
Co-authored-by: Nkezhenxu94 <kezhenxu94@163.com>

Fix official_analysis.oal url path at README.md

* Rename metric to metrics.

* Fixed test case execute failure issues.

* Fix doc.

* Fix typo

* Update new protocol

* Support new protocol at agent side.

* Fix test case.

* Make backend supports new trace protocol

* Fix tests.

* Make all new services available in gRPC.

* Fix bugs.

* Finish new document for v2 trace protocol.

* Fix wrong version requirement of zk

* Fix trace query bug.

* Find a client side dictionary bug.

* Fix register bugs.

* Fix break doc links.

@lemon @ascrutae I change the proto file path for preparing 6.0, but didn't change .net namespace. But I think if you sync the protocol submodule, you still need some changes.