[feat][cpp] Support multiple brokers in service URL

[BewareMyPower]

Motivation

It's a catchup for #3249.

Currently C++ client doesn't have strict validation on the service URL.
If multiple brokers are specified, only the 1st broker will be used.

Modifications

• Add ServiceURI to support configuring multiple brokers in the
  service URL. See ServiceURITest for how to configure it.
• Add ServiceNameResolver whose resolveHost method selects the
  next broker in a round robin way.
• Since the broker's address for topic lookup is no longer the service
  URL itself, to handle the case when proxy is enabled, a getBroker
  method (like the same method in Java's LookupService), which returns
  the future of a pair of logical and physical addresses, is added to
  replace lookupAsync.
• Apply ServiceNameResolver into ClientImpl and the
  LookupService implementations.
• Rename BinaryLookupServiceTest to LookupServiceTest and add
  testMultiAddresses to test both BinaryProtoLookupService and
  HTTPLookupService that all available brokers will be accessed in a
  round robin way.

Behavior Change

This PR also changes the behavior when the user passed service URL.
Before this PR, creating a Client object will succeed but the methods to
create a producer or consumer will return a failed Result. After this PR,
an invalid_argument exception will be thrown.

TODO

This is the 1st part to support multiple brokers. Even with this patch,
if one of these hosts is not available, the topic lookup will fail
immediately instead of trying other broker. Since this patch already
includes many code changes, I will push another patch to fix it.

Documentation

Check the box below or label this PR directly.

Need to update docs?

• doc-required
  (Your PR needs to update docs and you will update later)

• doc-not-needed
  (Please explain why)

• doc
  (Your PR contains doc changes)

• doc-complete
  (Docs have been already added)

[BewareMyPower]

The testWrongListener is affected, I will mark it as draft and fix it.

2022-08-18 13:23:38.989 INFO  [140182675973888] ConnectionPool:96 | Created connection for
/pulsar/pulsar-client-cpp/tests/ClientTest.cc:248: Failure
Expected equality of these values:
  ResultServiceUnitNotReady
    Which is: ServiceUnitNotReady
  client.createProducer(topic, producer)
    Which is: ConnectError

[BewareMyPower]

Draft this PR until the Python tests are fixed.

[BewareMyPower]

@RobertIndie @merlimat @rdhabalia @gaoran10 Could any of you take a second look?

[batilak]

Hi @BewareMyPower : this change supports multiple Broker URLs for brokers present in same cluster or it even supports brokers from different clusters?

As this is not clearly mentioned in documentation. thanks, ...

[BewareMyPower]

See my comment #3249 (comment)