eslint-parser: ES2020 features (#11815)

* chore: update espree test on nullish coalescing

* feat: add optional chaining support

* fix: adapt to estree AST shape

* chore: update lockfile

* add estree optional-chaining test fixtures

* address review comments

* chore: simplify smoke test

* export * support

Co-authored-by: Brian Ng <bng412@gmail.com>

packages/babel-parser/test/fixtures/estree/optional-chaining/optional-call-optional-call/input.js

@@ -0,0 +1 @@
+foo?.()?.()