feat: Add SharedBehavior class which handles the PartitionsFor method on consumers and producers

[dpcollins-google]

Diffbased on #276

[codecov]

Codecov Report

Merging #278 into master will decrease coverage by 0.88%.
The diff coverage is 42.47%.

@@             Coverage Diff              @@
##             master     #278      +/-   ##
============================================
- Coverage     71.80%   70.92%   -0.89%     
- Complexity      775      780       +5     
============================================
  Files           141      146       +5     
  Lines          4146     4244      +98     
  Branches        215      217       +2     
============================================
+ Hits           2977     3010      +33     
- Misses         1044     1107      +63     
- Partials        125      127       +2     

Impacted Files	Coverage Δ	Complexity Δ
...le/cloud/pubsublite/kafka/KafkaExceptionUtils.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)
...oogle/cloud/pubsublite/internal/ExtractStatus.java	44.44% <30.43%> (-33.34%)	4.00 <1.00> (-2.00)
...com/google/cloud/pubsublite/kafka/LiteHeaders.java	34.78% <34.78%> (ø)	4.00 <4.00> (?)
.../google/cloud/pubsublite/kafka/SharedBehavior.java	81.81% <81.81%> (ø)	3.00 <3.00> (?)
...oogle/cloud/pubsublite/kafka/RecordTransforms.java	84.61% <84.61%> (ø)	3.00 <3.00> (?)
.../google/cloud/pubsublite/kafka/PubsubLiteNode.java	100.00% <100.00%> (ø)	1.00 <1.00> (?)
...d/pubsublite/internal/BufferingPullSubscriber.java	82.05% <0.00%> (-3.67%)	4.00% <0.00%> (-4.00%)
... and 2 more

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