Keep extra parens around unit & tuples in arg pats

[brianrourkeboll]

Description

Another followup to #16079, et seq.

There are several scenarios where it is impossible to know whether the parentheses are required, or whether they may affect compilation, by looking only at the syntax. I addressed this for invocations in #17012, but not for definitions.

• Always keep extra parentheses around () in argument patterns.

  In the absence of additional type information, (()) (or ((())), etc.) may be compiled differently from () when used as an argument pattern in a method definition.

  (See unit elimination logic can lead to unutterable & unimplementable signatures #17611, Parenthesized/double unit literal () → (()) required in certain scenarios #16254.)

• Always keep extra parentheses around tuples in argument patterns.

  In the absence of additional type information, ((x, y)) (or (((x, y))), etc.) may be compiled differently from (x, y) in argument patterns.

Checklist

• Test cases added.
• Release notes entry updated.

[github-actions]

❗ Release notes required

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✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/9.0.100.md

[psfinaki]

Thanks for polishing this up!