nimsuggest: fix #96 ; enabled via --partialRecompilation since some cases cause crashes

[timotheecour]

/cc @Araq
this reopens #9715 as requested by @Araq but hides the feature under --partialRecompilation so only it's only enabled for users who want to try it out
reference:
this comment from @Araq #9721 (comment)

I liked your previous solution much better and the crashes could have been fixed, I think. The ModuleGraph can have multiple entry points, in theory there is not much to it.

description

• fixes project file update doesn't work nimsuggest#96
  docs say https://nim-lang.github.io/Nim/nimsuggest.html

There is some support so that you can throw random .nim files which are not part of myproject at Nimsuggest too, but usually the query refer to modules/files that are part of myproject.

this wasn't true until this PR
it's a very useful feature that allows you to handle nim files not covered by your initial project.nim

• refs no more projectfile.nim as argument nimsuggest#66
• refs Find project file PMunch/nimlsp#8

caveat

same caveat as mentioned in #9715 (comment) applies

note

tried to reopen #9715 using instructions in https://gist.github.com/robertpainsi/2c42c15f1ce6dab03a0675348edd4e2c but git push -f origin 70aa9613371081d52dfaba90fa12d5532b3e1ae1:pr_nimsuggest_fix_96 failed because I don't have credentials it seems

[Araq]

I prefer to fix the most pressing crashes and to avoid yet another flag.

[timotheecour]

done PTAL (reverted the hiding under a new flag)