feat: Allow expressions in LIMIT

[MazterQyou]

This PR adds support for parsing expressions (like placeholders or subqueries) in LIMIT. It also boxes a Query in Cte, following the same approach as with other Query instances.

[coveralls]

Pull Request Test Coverage Report for Build 2507500117

• 8 of 8 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.005%) to 89.762%

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Totals
Change from base Build 2448443641:	0.005%
Covered Lines:	8487
Relevant Lines:	9455

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💛 - Coveralls