`SyntaxTraversal.Traverse` → `ParsedInput.tryPick` (etc.)

[brianrourkeboll]

• Update most[^1] uses of the SyntaxTraversal.Traverse/SyntaxVisitorBase<_> API to one of the analogous APIs added to FCS in https://github.com/dotnet/fsharp/pull/16462 — usually ParsedInput.tryPick, occasionally also ParsedInput.tryNode or ParsedInput.tryPickLast.
• Update the code fix scaffold to use ParsedInput.tryPick.

Note: while SyntaxCollectorBase + walkAst could also theoretically be replaced by ParsedInput.fold, I have not done so in this PR.

[^1]: The one usage I didn't update is tryGetExplicitTypeInfo — this would in theory actually be quite easy to solve using ParsedInput.tryNode, except that I discovered that FCS doesn't actually call dive/pick for patterns (like it does for expressions and other node types) and uses List.tryPick instead, which means that the deepest matching pattern is not always returned. I may try to see if that's something that can be fixed in FCS.

[baronfel]

Holy smokes these look amazing. THANK YOU for taking the time to port us over to the new API - its already much cleaner and easier to follow what some of the matches are trying to do.

[baronfel]

Thanks again @brianrourkeboll - this looks awesome :)

[nojaf]

Great work @brianrourkeboll!