[scope-manager] should ignore parserOptions.ecmaVersion

[bradzacher]

See discussion in jsx-eslint/eslint-plugin-react#2882

There are only two cases in this project that we honour parserOptions.ecmaVersion, and both are in scope-manager:

typescript-eslint/packages/scope-manager/src/ScopeManager.ts

Lines 78 to 84 in 498f397

	public isStrictModeSupported(): boolean {
	return this.#options.ecmaVersion != null && this.#options.ecmaVersion >= 5;
	}
	public isES6(): boolean {
	return this.#options.ecmaVersion != null && this.#options.ecmaVersion >= 6;
	}

These usages were brought across when I forked eslint-scope.

However in the context of TS scope analysis - the ecmaVersion makes zero sense.
TS will never treat your code as if it's ES5 or lower - it is always (syntactically and semantically) "ESNext".

Whilst other parts of the ecosystem respects them - and they should continue to - our parser and scope analyser should (like TS itself) always treat code as if it is ESNext in terms of language features.

[JoshuaKGoldberg]

#5889 is merged into #5886; closing this issue now accordingly. It'll be released as a part of the v6 major release.