my desired metals features and improvements

[doofin]

todo:

• exhaustive match for tuples 
• show type only on val binding : improvement:don't show types for match case for showInferredType scalameta/metals#5284 (comment)
• type hint is too messy at "case" and method type parameter at call site
• selection expansion fix:selection expansion in comments scalameta/metals#4921
• auto complete word in comment
• Conflict with pprint in mdoc in worksheet scalameta/mdoc#732
• Expand Selection in comments for Scala 2 scalameta/metals#6109
• action to add Scala doc
• strip long type hints in "show type" feature scalameta/metals-feature-requests#372
• show only methods in symbols

code action:

• add docs