[Bigtable] CreateTableRequest equals and hashCode with unit test

[rahulKQL]

More information: #5066 (comment)

• Fixed CreateTableRequest#equals & hashCode
• Added unit test for equals, hashCode & toProto.

[rahulKQL]

@igorbernstein2 Please have a look

[rahulKQL]

@igorbernstein2 This PR is ready for another round of review, PTAL.

[codecov]

Codecov Report

Merging #5079 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@ Coverage Diff @@## master #5079 +/- ##
============================================
+ Coverage 50.38% 50.4% +0.02% - Complexity 23735 23785 +50 
============================================
Files 2248 2251 +3 Lines 226478 226785 +307 Branches 24954 24966 +12 ============================================
+ Hits 114113 114314 +201 - Misses 103772 103864 +92 - Partials 8593 8607 +14

Impacted Files	Coverage Δ	Complexity Δ
...d/bigtable/admin/v2/models/CreateTableRequest.java	85.18% <100%> (+10.99%)	8 <2> (+2)	⬆️
...n/java/com/google/cloud/bigquery/BigQueryImpl.java	80.21% <0%> (-3.89%)	58% <0%> (+5%)
...e/cloud/bigquery/testing/RemoteBigQueryHelper.java	62.5% <0%> (-1.14%)	6% <0%> (ø)
.../google/cloud/bigquery/spi/v2/HttpBigQueryRpc.java	6.1% <0%> (-0.83%)	2% <0%> (ø)
.../talent/v4beta1/stub/EventServiceStubSettings.java	78.48% <0%> (-0.27%)	10% <0%> (ø)
...alent/v4beta1/stub/ProfileServiceStubSettings.java	75.32% <0%> (-0.16%)	16% <0%> (ø)
...talent/v4beta1/stub/TenantServiceStubSettings.java	80% <0%> (-0.16%)	15% <0%> (ø)
...alent/v4beta1/stub/CompanyServiceStubSettings.java	80% <0%> (-0.16%)	15% <0%> (ø)
...t/v4beta1/stub/ApplicationServiceStubSettings.java	80.15% <0%> (-0.16%)	15% <0%> (ø)
...ud/talent/v4beta1/stub/JobServiceStubSettings.java	72.48% <0%> (-0.15%)	18% <0%> (ø)
... and 17 more

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