fix(eslint-plugin): [prefer-optional-chain] handling first member expression

[yeonjuan]

There is a false negative when member expression comes first.

foo.bar && foo.bar.baz;  // no error

[typescript-eslint]

Thanks for the PR, @yeonjuan!

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[codecov]

Codecov Report

Merging #2156 into master will decrease coverage by 0.05%.
The diff coverage is 41.66%.

@@            Coverage Diff             @@
##           master    #2156      +/-   ##
==========================================
- Coverage   93.56%   93.50%   -0.06%     
==========================================
  Files         171      171              
  Lines        7811     7809       -2     
  Branches     2229     2229              
==========================================
- Hits         7308     7302       -6     
+ Misses        244      243       -1     
- Partials      259      264       +5     

Flag	Coverage Δ
#unittest	93.50% <41.66%> (-0.06%)	⬇️

Impacted Files	Coverage Δ
packages/eslint-plugin-tslint/src/rules/config.ts	97.36% <0.00%> (-2.64%)	⬇️
...nt-plugin/src/rules/indent-new-do-not-use/index.ts	98.13% <0.00%> (-0.27%)	⬇️
...es/eslint-plugin/src/rules/no-use-before-define.ts	97.14% <0.00%> (-1.43%)	⬇️
...s/eslint-plugin/src/rules/prefer-optional-chain.ts	95.09% <ø> (ø)
.../experimental-utils/src/eslint-utils/RuleTester.ts	9.09% <0.00%> (+0.20%)	⬆️
packages/parser/src/analyze-scope.ts	95.13% <0.00%> (-0.38%)	⬇️
...pt-estree/src/create-program/createWatchProgram.ts	78.60% <0.00%> (ø)
...kages/eslint-plugin/src/rules/no-empty-function.ts	84.00% <50.00%> (-4.47%)	⬇️
...t-plugin/src/rules/adjacent-overload-signatures.ts	93.02% <100.00%> (ø)
packages/eslint-plugin/src/rules/array-type.ts	94.28% <100.00%> (ø)
... and 1 more

[yeonjuan]

It seems to affect the current code.
I'm not sure the ignoring first member expression is bug or not. If it's a bug I'll change them base on this PR.

[bradzacher]

LGTM - thanks!