Add PLACEMENT_AWARE partition group support.

[enozcan]

Adds placement aware partition group strategy support to form partition groups based on AWS placement groups. The strategy provides availability within a single zone as high as possible by spreading partitions and their replicas across different racks.

• Related PRD
• Related TDD
• Core: Add PLACEMENT_AWARE partition group strategy. hazelcast#18048

[leszko]

Added some comments. The code looks fine, most comments are actually to README.

Additionally, I think we should merge PR after hazelcast/hazelcast#18048

[enozcan]

@leszko PTAL

[enozcan]

Per hazelcast/hazelcast#18048 (comment), replaced @ notation in PPG group name by -

[leszko]

Added 3 comments to README. Other than that, LGTM 👍

[enozcan]

I noticed that with the current setup it keeps retrying even after 404 response is received. This causes instances to start after ~15 seconds of delay with 5 retry count - even an instance does not belong to a placement group. As the current rest client expects only HTTP_OK and assumes failed otherwise, the rest client needs some refactoring to overcome this.

I added the required changes to this PR via 88849d7 but it might be difficult to review them all together here. I can separate this into two different PRs: 1) Rest client refactoring and 2) Placement Aware support.

@leszko Please let me know your opinion and I'm sorry for the inconvenience.

What 88849d7 does is:

• Wrapping response messages along with the response code into RestClient.Response object.
• Making rest calls to expect certain response codes (via RestClient#expectResponseCodes(Integer... codes)) and if responses do not match, then throw exception. By default, 200 is the only expected code - the same as the current behavior.
• Allowing rest clients to read error messages also (RestClient#read). With the current versions clients can only read response bodies returned with 200.
• When resolving placement groups, it retries until 200 or 404 is returned. If it failed to get none of them after retries, it logs a warning.

[leszko]

Added one minor comment. Other than that, looks good. Thanks @enozcan for the changes.

[alparslanavci]

LGTM 👍 Thanks for the clean code.