Support socks5 proxy

[Technoboy-]

Motivation

Some user networks may have a layer of socks5 proxy, so the client side is added socks5 proxy handler to support socks5 protocal.

Modifications

Add Socks5ProxyHandler in ConnectionPool as the first handler for producer and consumer.

Does this pull request potentially affect one of the following parts:

If yes was chosen, please highlight the changes

• Dependencies (does it add or upgrade a dependency): (yes, add)
• The public API: (yes)
• The schema: (no)
• The default values of configurations: (yes)
• The wire protocol: (no)
• The rest endpoints: ( no)
• The admin cli options: (no)
• Anything that affects deployment: (no)

Documentation

• Does this pull request introduce a new feature? (yes)

How to use

      // # 1
      PulsarClient
                .builder()
                .serviceUrl("pulsar://service-url:6650")
                .socks5ProxyAddress(new InetSocketAddress("localhost", 11080)) // change to proxy host and port
                .socks5ProxyUsername("username")  // If there is a username and password
                .socks5ProxyPassword("password")  
                .build()
      
     // # 2
     PulsarClient
                .builder()
                .serviceUrl("pulsar://service-url:6650")
                .build()
     Start client with '-D' like : -Dsocks5Proxy.address=http://localhost:11080 -Dsocks5Proxy.username='username' -DsocksProxy.password='password'

[Anonymitaet]

@Technoboy- many thanks for your details!

As we called just now, could you please help add docs and ping me review?

You might need to:

1. Check to which versions the doc will be added.

• If you want to modify master doc, go here.
• If you want to modify versioned docs, go here.

2. Add docs (3 parameters and add necessary descipritons) here
   

3. Besides, this is the doc architecture for various clients, you can take it as a refernece.

---

Tip

Java Client API website (doc) is automatically generated from its code.

If you add descriptions (like you did here ), you've already added docs for the Java API website. (@codelipenghui so do not remove the component/documentation label from this PR, I've labeled it back. Anyway many thanks for your label :-D)

[Technoboy-]

@Technoboy- many thanks for your details!

As we called just now, could you please help add docs and ping me review?

You might need to:

1. Check to which versions the doc will be added.

• If you want to modify master doc, go here.
• If you want to modify versioned docs, go here.

1. Add docs (3 parameters and add necessary descipritons) here
   
2. Besides, this is the doc architecture for various clients, you can take it as a refernece.

Tip

Java Client API website (doc) is automatically generated from its code.

If you add descriptions (like you did here ), you've already added docs for the Java API website. (@codelipenghui so do not remove the component/documentation label from this PR, I've labeled it back. Anyway many thanks for your label :-D)

Done, please help check client-libraries-java.md .

[Anonymitaet]

Approved from doc perspective

[codelipenghui]

Great Job @Technoboy- , I just left some comments about the tests.

[codelipenghui]

@Anonymitaet I noticed you have added the component/documentation tag, we are using this for indicating the PR is only the documentation change? or the PR has documentation change?

[gaoran10]

Great work! Left some comments.

Could you check the code format? Such as the class Socks5Server.

[gaoran10]

LGTM

[codelipenghui]

/pulsarbot run-failure-checks

[codelipenghui]

@Technoboy- Looks the failed the tests are related to this change, PTAL.

[Technoboy-]

/pulsarbot run-failure-checks