fix(typescript-estree): correct ChainExpression interaction with parentheses and non-nulls

[bradzacher]

I did some alignment testing against babel and found they handled some things differently. I decided their way was better, so updating the representation to match.

Previously:

• we emitted a different AST for pre-3.9 and post-3.9
• we treated TSNonNullExpression as a breakage in the chain, meaning that the ChainExpression would not move up through them.

Now:

• we emit the same AST regardless of TS version
• we treat TSNonNullExpression as a ChainElement, so the ChainExpression always moves past them in the tree

[typescript-eslint]

Thanks for the PR, @bradzacher!

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[codecov]

Codecov Report

Merging #2380 into v4 will decrease coverage by 0.15%.
The diff coverage is 56.09%.

@@            Coverage Diff             @@
##               v4    #2380      +/-   ##
==========================================
- Coverage   92.96%   92.81%   -0.16%     
==========================================
  Files         286      286              
  Lines        9046     9048       +2     
  Branches     2514     2509       -5     
==========================================
- Hits         8410     8398      -12     
- Misses        305      320      +15     
+ Partials      331      330       -1     

Flag	Coverage Δ
#unittest	92.81% <56.09%> (-0.16%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...pt-estree/src/ts-estree/estree-to-ts-node-types.ts	100.00% <ø> (ø)
...n/src/rules/no-non-null-asserted-optional-chain.ts	41.93% <21.73%> (-50.93%)	⬇️
...s/eslint-plugin/src/rules/prefer-optional-chain.ts	94.23% <100.00%> (+0.05%)	⬆️
packages/typescript-estree/src/convert.ts	98.37% <100.00%> (+0.01%)	⬆️
packages/typescript-estree/src/node-utils.ts	97.68% <100.00%> (+0.98%)	⬆️