allow to customize the httpclient used to create S3PinotFS

[klsince]

This PR exposes some configs to customize the httpclient used to create s3client, when to init the S3PinotFS.

Release Note

the exposed httpclient configs are
httpclient.maxConnections, e.g. 100 (this is more required for now. when we increased helixExecutorTask thread number via STATE_TRANSITION.maxThreads to load segments with more threads, some threads threw exceptions about timeout to get a http conn to download raw segments from deep store)

httpclient.socketTimeout, e.g. 10s
httpclient.connectionTimeout, e.g. 1m20s
httpclient.connectionTimeToLive, e.g. ..
httpclient.connectionAcquisitionTimeout, e.g. ..

[npawar]

lgtm.
I didn't realize we've already introduced PT notations in DateTimeFunctions. Was going to suggest we stick to the period strings we use in other places like realtime thresholds, periodic task frequencies (12h, 3m30s). But this sounds fine to me.
Please add these new props to https://docs.pinot.apache.org/basics/data-import/pinot-file-system/amazon-s3#server-config

[klsince]

I didn't realize we've already introduced PT notations in DateTimeFunctions. ...

Thanks for the context. I was using PT format as Duration is what the httpClientBuilder takes. I'll make it compatible with the two formats, as it's better to keep format of timeout/period configs consistent

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 82.50000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 70.44%. Comparing base (5d0089a) to head (e659bc0).
Report is 2817 commits behind head on master.

Files with missing lines	Patch %	Lines
...a/org/apache/pinot/plugin/filesystem/S3Config.java	86.84%	0 Missing and 5 partials ⚠️
.../org/apache/pinot/plugin/filesystem/S3PinotFS.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #10369      +/-   ##
============================================
+ Coverage     67.87%   70.44%   +2.57%     
- Complexity     5742     6005     +263     
============================================
  Files          1521     2036     +515     
  Lines         80305   110444   +30139     
  Branches      12826    16793    +3967     
============================================
+ Hits          54506    77804   +23298     
- Misses        21957    27202    +5245     
- Partials       3842     5438    +1596     

Flag	Coverage Δ
integration1	24.45% <0.00%> (?)
integration2	24.45% <0.00%> (?)
unittests1	67.88% <ø> (+0.01%)	⬆️
unittests2	13.78% <82.50%> (?)

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[npawar]

lgtm otherwise