Add support for validate_sql method to BigQuery #7816

Job	Run time
code-quality	1m 34s
build packages	18s
unit test / python 3.8	1m 3s
unit test / python 3.9	56s
unit test / python 3.10	1m 10s
unit test / python 3.11	52s
verify packages / python 3.8 / ubuntu-latest	57s
verify packages / python 3.9 / ubuntu-latest	58s
verify packages / python 3.10 / ubuntu-latest	53s
verify packages / python 3.11 / ubuntu-latest	1m 13s
verify packages / python 3.8 / macos-latest	1m 43s
verify packages / python 3.9 / macos-latest	1m 32s
verify packages / python 3.10 / macos-latest	2m 53s
verify packages / python 3.11 / macos-latest	1m 32s
verify packages / python 3.8 / windows-latest	2m 11s
verify packages / python 3.9 / windows-latest	4m 5s
verify packages / python 3.10 / windows-latest	2m 53s
verify packages / python 3.11 / windows-latest	2m 49s
	29m 32s

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