This is a continuation of

• [BREAKING CHANGE] Change Atom to Atom<'a> to make it safe oxc#2497
• Make Atom safe and faster oxc#2295

Where the requirements are:

Make our own version of Atom<'a> and CompactString.

These 2 types should be immutable and inline-able. The size of these two types (either 16 or 32 bytes) should be dependent on real world statistics of the length of identifiers.