Add support for mysql 'SHOW CREATE VIEW' statement

[mirober]

Support for show create view.

This may be useful for apache/datafusion#2857.

[alamb]

Thanks @mrob95

[coveralls]

Pull Request Test Coverage Report for Build 2641340203

• 3 of 4 (75.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.006%) to 89.884%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/parser.rs	1	2	50.0%

Totals
Change from base Build 2631347546:	-0.006%
Covered Lines:	8876
Relevant Lines:	9875

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💛 - Coveralls

[alamb]

Thanks @mrob95 !