*Motivation*

Bump the development version to 2.6.0-SNAPSHOT

* Removed managed-ledger-shaded artifact

* Fixed dep artifact renaming error

 ### Motivation

Offloader typically involves a new storage system, which usually involves dependencies that
might be conflicting with the dependencies of Pulsar. We want to package offloader implementations
as what we did for connectors, so people can decide which offloader to use and only include it.
People would also become easier to write its offloader if needed.

 ### Changes

- Update `tiered-storage/jcloud` to package it using nifi-nar plugin.
- Add bunch of utils in managed-ledger to locate offloader nar packages and load `LedgerOffloaderFactory` from corresponding NAR package.
- Add a new distribution module to package offloaders into one distribution, as what we did for connectors.
- Update pulsar-all image to include offloaders

 ### NOTES

This change doesn't get rid of jcloud-shaded. because jcloud is using `ServiceLoad` and Guice injection. It makes
things very tricky on class loading. Not attempt to address the problem any time soon. We can pin `jcloud-shaded` version
as what we did for `protobuf-shaded` in next release.

*Motivation*

We shipped two distributions : server & io-connectors. For people who
run pulsar in docker, we need to put all the built-in connectors into
the docker, so that all built-in connectors are available to be used.

*Solution*

Introduce a `pulsar-all` image to include built-in connectors.

Named it as `pulsar-all` to allow include more pluggable components later, for example, offloaders.

### Motivation

We need to package Pulsar IO connectors as part of the release. 
We provide a new file `apache-pulsar-io-connectors-$VERSION-bin.tar.gz` that contains [NAR](https://medium.com/hashmapinc/nifi-nar-files-explained-14113f7796fd).

In subsequent PR, I'll add the logic to load and use these archives.

Signed-off-by: NSijie Guo <sijie@apache.org>

Remove pulsar-common dependency from pulsar-io-core module and cleanup pulsar-common dependency references (#2020)

*Motivation*

With pulsar-common shading in pulsar-client, conflicts observed when using pulsar-client with connectors. Because pulsar-client shades its dependencies,
while pulsar-io implementations pull in pulsar-common which depends on non-shaded dependencies.

*Changes*

- Move KeyValue class to pulsar-io-core, since all pulsar-io is using it.
- Remove pulsar-common from all pulsar-io implementation modules
- Cleanup all direct usage of pulsar-common when pulsar-client-original is in the place.

* begin renaming process

* more class and directory renames

* move Record classes into pulsar-io

* apply rename to Maven configs

* rename java imports

* update versions in maven configs

* add missing imports

* remove Message class from pulsar-io

* add missing import

* add Reflections util import

* add Utils import

* add missing Record import

* supply missing Record imports

* Added Kafka Source and Kafka Sink to Pulsar Connect

* Standardize on kafka versions for compat and connect

* Added Cassandra Sink Connector

* Added Pulsar Connect interfaces that define connectors that push data into pulsar and take data from pulsar

* Added Twitter connector

* Added hbc core version mapping

* Addressed comments

* Fixed build

* Fixed license header

- Remove function-composition

* Relocate instance and spawner to be under `runtime` package
* fix the pom files and travis build

* Split functions module into api/runtime/api-examples

* Move `org.apache.pulsar.functions.api` package from runtime to api package

* Updates headers with ASF source files header

* change license to additional files