fix(eslint-plugin): [no-extra-non-null-assertion] dont report for assertions not followed by the optional chain

[bradzacher]

Fixes #2166

[typescript-eslint]

Thanks for the PR, @bradzacher!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

Merging #2167 into master will decrease coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2167      +/-   ##
==========================================
- Coverage   93.55%   93.47%   -0.08%     
==========================================
  Files         171      171              
  Lines        7799     7813      +14     
  Branches     2225     2229       +4     
==========================================
+ Hits         7296     7303       +7     
  Misses        244      244              
- Partials      259      266       +7     

Flag	Coverage Δ
#unittest	93.47% <100.00%> (-0.08%)	⬇️

Impacted Files	Coverage Δ
...nt-plugin/src/rules/no-extra-non-null-assertion.ts	100.00% <100.00%> (ø)
...kages/eslint-plugin/src/rules/no-empty-function.ts	84.00% <0.00%> (-4.47%)	⬇️
packages/eslint-plugin-tslint/src/rules/config.ts	97.36% <0.00%> (-2.64%)	⬇️
...es/eslint-plugin/src/rules/no-use-before-define.ts	97.14% <0.00%> (-1.43%)	⬇️
packages/eslint-plugin/src/util/types.ts	81.21% <0.00%> (-1.22%)	⬇️
...plugin/src/rules/explicit-module-boundary-types.ts	89.23% <0.00%> (-0.70%)	⬇️
packages/parser/src/analyze-scope.ts	95.13% <0.00%> (-0.38%)	⬇️
...nt-plugin/src/rules/indent-new-do-not-use/index.ts	98.13% <0.00%> (-0.27%)	⬇️
...s/eslint-plugin/src/rules/prefer-optional-chain.ts	95.09% <0.00%> (ø)
.../experimental-utils/src/eslint-utils/RuleTester.ts	9.09% <0.00%> (+0.20%)	⬆️
... and 1 more

[fregante]

Thanks Brad ✨