support MySQL quote style like BEGIN

[miuy56dc]

Support MySQL quote https://dev.mysql.com/doc/refman/8.0/en/keywords.html

[coveralls]

Pull Request Test Coverage Report for Build 187886211

• 16 of 16 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.05%) to 91.79%

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Totals
Change from base Build 186377189:	0.05%
Covered Lines:	4405
Relevant Lines:	4799

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💛 - Coveralls

[nickolay]

This looks good, but I'd prefer the test for back-ticked identifiers to be in parse_identifiers or in a separate test, instead of being combined with the test for AUTO_INCREMENT.

[nickolay]

Excellent, thanks! I noticed (after merging) that https://dev.mysql.com/doc/refman/8.0/en/identifiers.html says MySQL also supports normal "double quotes" in ANSI_QUOTES mode, while with this patch the MySQL dialect doesn't seem parse those.