This PR add a new rule that remove `if` expressions and convert them
into an equivalent expression.

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Co-authored-by: jiwonz <jiwonz0113@gmail.com>

This avoids bugs were the evaluator was replacing `-0` results with
only `0`.

This rule converts `continue` statements into an equivalent construct
that only uses `break` statements.

Co-authored-by: jiwonz <jiwonz0113@gmail.com>

Add a new rule `remove_floor_division` to remove usage of `//` in
expressions or compound assignments (`//=`). The code is replaced with a
`math.floor` call on a regular division.

Remove the extra space that is added in front of comments. This makes it
possible to generate comments like `--!native` which are useful in Luau.