Apply timeout to simplification

[GrahamTheCoder]

Problem

#877
A deeply nested single expression seemed to cause this issue.

Solution

Currently just skips simplification when it takes longer than the configurable timeout. This at least allows the conversion to proceed. The first few things I tried give me the sense this is going to be hard to actually fix, even with a PR to roslyn itself, so I'll merge the workaround for now and get that released

• Get a benchmark test set up for this and experiment with different approaches:
  • Simplify leaf nodes first and work up.
  • Skip simplifying subparts of a name, just the outer one may be enough
  • Try adding new lines
  • Try extracting sub expressions into their own field

Notes

• Even simplifying with the simplify annotation only on the namespace node takes 48.5s
• All the time seems to be in GetOriginalSymbol info. I believe that for each identifier, it essentially rebinds the entire expression in order to get the original symbol.
• Very similar sort of issue here: https://lightrun.com/answers/omnisharp-omnisharp-vscode-omnisharp-gets-stuck-at-100-cpu-when-analyzing-complex-automapper-profiles