fix(parser): fix crash when visiting decorators in parameters

[armano2]

This PR is fixes crashes in no-unused-vars for decorators in non identifier function parameters, and fixes issue with no-shadow for this in functions

#122 (comment)

i think we should merge this after #234 (snapshots for scope analysis)

fixes: #207

[codecov]

Codecov Report

Merging #237 into master will increase coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #237      +/-   ##
=========================================
+ Coverage   94.53%   94.6%   +0.07%     
=========================================
  Files          63      63              
  Lines        2761    2762       +1     
  Branches      718     719       +1     
=========================================
+ Hits         2610    2613       +3     
  Misses         57      57              
+ Partials       94      92       -2

Impacted Files	Coverage Δ
packages/parser/src/visitor-keys.ts	100% <ø> (ø)	⬆️
packages/eslint-plugin/src/rules/no-unused-vars.ts	92.85% <ø> (+4.97%)	⬆️
packages/parser/src/analyze-scope.ts	95.76% <100%> (+0.09%)	⬆️

[bradzacher]

don't know a heap about the scope manager yet, but the CI passes and I don't see anything stupid in the code, so I'm happy with it 😄

[armano2]

Crash is related to eslint not beeing able to set parent to decorators in parameters.
we was creating references while visiting it with pattern-visitor, but nodes was not traversable.

eslint traverse nodes base on structure defined in visitor-keys, and setts up parent for nodes.

no-unused-vars is relying on parent of nodes set properly

2nd issue was that TSParameterProperty was not visitable and rule itself was reporting unused variables bacause we was not making references for decorators