PIP-13-2/3: support regex based subscription

[zhaijack]

This change is based on work of #1103, which already contains the first 3 commits there. In this PR, the commits after the first 3 are for this sub-task.

Motivation

This is a second sub-task for pip-13, which would like to leverage the first task to support regex based subscription.

Modifications

• add subscribe methods with regex pattern in PulsarClient and PulsarClientImpl.
• add PatternTopicsConsumerImpl, which extends TopicsConsumerImpl.
• add a binary proto command to get topics under a namespace.
• add a test to verify.

Result

old methods behaviour not changed,
user could use new method to subscribe to topics based on regex pattern

[zhaijack]

retest this please

[sijie]

If I remembered correctly, we are bumping the protocol version in one of your other pull requests, if this change is going to be merged with that pull request in same release, I would suggest update the comment of that protocol version with these two new commands.

Otherwise, we have to bump the protocol version.

[zhaijack]

Yes. there was #1066 to get the last message id, which is marked as 1.22.

[sijie]

If this change is going to be merged at 2.0, there might some changes to be coordinated here, because cluster might be removed at 2.0, so that we don't need to include cluster here.

this is just a FYI. you don't need to change at this moment. /cc @merlimat

[zhaijack]

Thanks.

[sijie]

@zhaijack the overall change looks good. but I will take a closer review once #1103 is in.

[zhaijack]

would like to close this one and open a new PR.