LibJS: Add ECMA-262 section/title/URL comments almost everywhere

As mentioned on Discord earlier, we'll add these to all new functions
going forward - this is the backfill. Reasons:

- It makes you look at the spec, implementing based on MDN or V8
  behavior is a no-go
- It makes finding the various functions that are non-compliant easier,
  in the future everything should either have such a comment or, if it's
  not from the spec at all, a comment explaining why that is the case
- It makes it easier to check whether a certain abstract operation is
  implemented in LibJS, not all of them use the same name as the spec.
  E.g. RejectPromise() is Promise::reject()
- It makes it easier to reason about vm.arguments(), e.g. when the
  function has a rest parameter
- It makes it easier to see whether a certain function is from a
  proposal or Annex B

Also:

- Add arguments to all functions and abstract operations that already
  had a comment
- Fix some outdated section numbers
- Replace some ecma-international.org URLs with tc39.es

Userland/Libraries/LibJS/Token.cpp

@@ -203,7 +203,7 @@ bool Token::is_identifier_name() const
 {
     // IdentifierNames are Identifiers + ReservedWords
     // The standard defines this reversed: Identifiers are IdentifierNames except reserved words
-    // https://www.ecma-international.org/ecma-262/5.1/#sec-7.6
+    // https://tc39.es/ecma262/#prod-Identifier
     return m_type == TokenType::Identifier
         || m_type == TokenType::Await
         || m_type == TokenType::BoolLiteral