feat: Allow to use >> and << binary operators in Generic dialect (#553)

[ovr]

Hello!

Thanks

[coveralls]

Pull Request Test Coverage Report for Build 2803601720

• 8 of 8 (100.0%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.07%) to 89.835%

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Files with Coverage Reduction	New Missed Lines	%
tests/sqlparser_postgres.rs	1	98.6%

Totals
Change from base Build 2507685551:	0.07%
Covered Lines:	8528
Relevant Lines:	9493

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💛 - Coveralls