Move inline JS to external scripts

[masteradhoc]

Describe the bug

In #562 dd' already did already a lot work to get the inline JS to external scripts.
We should take over those commits and see if further adjustments are needed.

At the same time we should also check if the code is valid to WP Standards.

Steps to Reproduce

..

Screenshots, screen recording, code snippet

No response

Environment information

No response

Please confirm that you have searched existing issues in this repository.

Yes

Please confirm that you have tested with all plugins deactivated except Two-Factor.

Yes

[aslamdoctor]

I would like to work on this issue.

[aslamdoctor]

@masteradhoc the PR is ready #814