Add type parmeters to bqfakes

[stephen-soltesz]

This change adds row type parameters to the bqfake types. This change allows injecting arbitrary row result types for testing when using bqfake.NewQueryReadClient[Row]() and preserves previous behavior for bqfake.NewClient().

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 1241

• 20 of 20 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 94.495%

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Totals
Change from base Build 1238:	0.01%
Covered Lines:	2180
Relevant Lines:	2307

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💛 - Coveralls