Organize test suites in `swayfmt`

[eureka-cpu]

• parens
• block
• array Adds multiline formatting for array #2593 @eureka-cpu
• asm
• return
• conditionals
  • if/else Adds formatting for long conditional statements #2597 & Adds formatting for if_else control flow blocks #2564 @eureka-cpu
  • match Adds better formatting to match_branch_kind #2539 & Adds multiline formatting for match statements in sfv2 #2530 @eureka-cpu
• while
• index
• tuple field projection
• ref & deref
• bitwise operators
• comparison operators
• logical operators
• reassignment
• Add comment tests for expr in sfv2 #2497

Edit: Extending this to re-organizing all tests in swayfmt

[eureka-cpu]

Lower priority but tests that are in swayfmt/tests/mod.rs need to be broken up into their respective item directories if they are only testing individual formatting of items.

[JoshuaBatty]

I'm not sure how much of this is still relevant. A once over cleaning up the test infra for sway-fmt while checking that all types are covered in the test suite is probably a good idea to do still.