Replace double quote to single quote

[devgony]

Goal

Let's use single quote only for sql literal string

SELECT 'literal';

Todo

• refactor: replace double quote to single quote

Next

• fix translate to handle double qoute for Identifier

[coveralls]

Pull Request Test Coverage Report for Build 3398899427

• 52 of 53 (98.11%) changed or added relevant lines in 7 files are covered.
• 7 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.02%) to 97.86%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core/src/ast/ast_literal.rs	2	3	66.67%

Files with Coverage Reduction	New Missed Lines	%
core/src/executor/aggregate/mod.rs	7	81.82%

Totals
Change from base Build 3393980888:	-0.02%
Covered Lines:	38495
Relevant Lines:	39337

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💛 - Coveralls

[panarch]

I wasn't aware of that SQL handles single quoted & double quoted differently.
Thanks a lot! Looks all nice