Spinning off of #1033

Rules that need to have support added for optional chaining.
This list was based on a simple grep for MemberExpression and CallExpression, I haven't validated anything beyond that. There are probably extra rules that could do with support as well that don't check MemberExpression and CallExpression.

Rules that require a simple one-line change (i.e. adding a selector):

• consistent-type-assertions (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• explicit-function-return-type (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• func-call-spacing (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• no-array-constructor (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• no-floating-promises (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• no-inferrable-types (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• no-misused-promises (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• no-require-imports (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• no-var-requires (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• prefer-for-of (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• prefer-includes (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• prefer-readonly (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• prefer-regexp-exec (feat(eslint-plugin): optional chain support in rules (part 1) #1253)
• prefer-string-starts-ends-with (feat(eslint-plugin): [pref-str-starts/ends-with] optional chain support #1357)
• require-array-sort-compare (feat(eslint-plugin): more optional chain support in rules #1363)
• unbound-method (feat(eslint-plugin): more optional chain support in rules #1363)

Rules that require a larger enhancement to support (i.e. new feature in rule):

• no-unnecessary-condition (feat(eslint-plugin): [no-unnec-cond] check optional chaining #1315)

Extension rules that will be a pain to update (i.e. base extension rewrite):

• indent / indent-new-do-not-use
• no-extra-parens
  • This one will be a huge pain, and I believe it will involve us duplicating the base rule. The logic is relatively complex, so this is a non-trivial task.
• no-unused-vars

Broken rules due to ESLint not supporting the new AST nodes:

• camelcase [camelcase] False positive with optional chaining #1196
• no-restricted-globals [no-restricted-globals] False positive with optional chaining #1090
• no-undef [no-undef] False positive with optional chaining #1116
• no-unused-expressions [no-unused-expressions] False positive with optional chaining #1138
• no-use-before-define [no-use-before-define] False positive with optional chaining #1104