Add support for TOP before ALL/DISTINCT

[yoavcloud]

Adds support for dialects (Redshift) that expect the TOP keyword in a SELECT statement to appear before the ALL/DISTINCT option. For example: SELECT TOP 2 DISTINCT FROM tbl; https://docs.aws.amazon.com/redshift/latest/dg/r_SELECT_list.html

[coveralls]

Pull Request Test Coverage Report for Build 11707166854

Details

• 23 of 25 (92.0%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 89.391%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/dialect/mod.rs	1	2	50.0%
src/dialect/redshift.rs	1	2	50.0%
<!--	Total:	23	25	92.0%	-->

Totals
Change from base Build 11707125112:	0.0%
Covered Lines:	30587
Relevant Lines:	34217

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💛 - Coveralls

[alamb]

Thanks @yoavcloud and @iffyio