*Motivation*

Since the helm chart is already moved to [pulsar-helm-chart](https://github.com/apache/pulsar-helm-chart),
remove the duplicated code in the main repo and update the documentation to point to the chart repo.

*Motivation*

Currently we manage multiple different repositories for different components and clients.
We should update README to reflect the current state.

- updating README.md to call out that JDK 11 is supported instead of only listing JDK 1.8 / Java 8

Resolves: update-readme-java-11-doc

[Issue 4175] [pulsar-function-go] Add Go Function heartbeat (and gRPC service) for production usage (#6031)

Partial fix required for #4175. 
Addresses issue documented here: https://github.com/grpc/grpc-go/issues/3310
Part of ongoing work to add the gRPC service for heartbeat functionality and related support for running Go functions. 

### Motivation
Progress was blocked by the issue documented above. 

### Modifications

1. Updated ./generate.sh script in pulsar-function-go module to use the grpc plugin. 
2. Rebuilt Go gRPC files using the grpc plugin. This updated the proto version and was mostly an additive change that included adding the new registration methods required for creating the Go gRPC service. 

### Verifying this change

- Unable to test changes because Go tests were already failing. Currently investigating. 
- More testing will be done in subsequent commits because the Go gRPC functionality is not yet complete. (Should be low impact.)

When compiled with maven version 3.0.4, it failed and report error message as follow: 
```
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:3.0.0-M3:test (default-test) on project pulsar-client-api: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:3.0.0-M3:test failed: Unable to load the mojo 'test' (or one of its required components) from the plugin 'org.apache.maven.plugins:maven-surefire-plugin:3.0.0-M3': com.google.inject.ProvisionException: Guice provision errors:
[ERROR] 
[ERROR] 1) No implementation for org.codehaus.plexus.languages.java.jpms.LocationManager was bound.
[ERROR] while locating org.apache.maven.plugin.surefire.SurefirePlugin
[ERROR] at ClassRealm[plugin>org.apache.maven.plugins:maven-surefire-plugin:3.0.0-M3, parent: sun.misc.Launcher$AppClassLoader@5c647e05]
[ERROR] while locating org.apache.maven.plugin.Mojo annotated with @com.google.inject.name.Named(value=org.apache.maven.plugins:maven-surefire-plugin:3.0.0-M3:test)
[ERROR] 
[ERROR] 1 error
[ERROR] role: org.apache.maven.plugin.Mojo
[ERROR] roleHint: org.apache.maven.plugins:maven-surefire-plugin:3.0.0-M3:test
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginContainerException
[ERROR] 
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR]   mvn <goals> -rf :pulsar-client-api

```

Error reference: 
`https://stackoverflow.com/questions/53211941/unable-to-load-the-mojo-test-org-apache-maven-pluginsmaven-surefire-plugin`

When compiled with maven 3.3.3, it failed and report error message as follow: 
```
[ERROR] Failed to execute goal net.alchim31.maven:scala-maven-plugin:4.0.1:add-source (default) on project flink: The plugin net.alchim31.maven:scala-maven-plugin:4.0.1 requires Maven version 3.3.9 -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginIncompatibleException
[ERROR] 
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR]   mvn <goals> -rf :flink

```


Only Maven 3.3.9+, the project can build success.

* Remove old Pulsar website

* Remove `site/` reference

Intellij needs the lombok plugin to generate the code (getter, setter, data etc) used in this project.

* Clarify version match requirements between Go and C++ client librarires

* Document how to see local changes

* Link to docs README

* Move warning out from `go get` paragraph

* Removed mentions to incubator-pulsar

* Removed DISCLAIMER link from offloaders package

* Trigger build

* Updates headers with ASF source files header

* change license to additional files