fix: disallow updating built-in package managers

[jardon]

• check for built-in and error
• add english translation for error

[kbdharun]

The implementation LGTM, initially if I recollect correctly we allowed editing the built-in package managers so that users can edit the arguments as per their requirement, IG they can still duplicate and edit it now or open a PR to the custom apx stacks repo (so it benefits all users).

[kbdharun]

@mirkobrombin This branch is upto date but still it is waiting for sonar action, can you go to https://github.com/Vanilla-OS/apx/settings and branch protection rules then remove the requirement from there.

[mirkobrombin]

We dropped that idea some time ago, they should make they own package managers with different names