Make Translation entity module JS follow newer core rules

#1810386: Create workflow to setup multilingual for entity types, bundles and fields added the translation entity interface, it's js isn't following newer core standards for it.

Declared and attached the JS with hook_library_info(), used event delegation on the admin screen so that it'll somehow scale for real sites. It's still not good enough though.

The table UI is bad from a code perspective, it shouldn't be using tables or at least it needs classes to be added on cells to make all those selectors much faster to match. Not really in the scope of this issue i'd say.