Add ability to mark sequences as read-only

[shaheerk94]

Checked for duplicates

Yes - I've already checked

Alternatives considered

Yes - and alternatives don't suffice

Related problems

A pretty common use case is appearing on psyche where sequences are "complete" and users want to be able to mark them as read-only to avoid accidental edits.

Describe the feature request

Add the ability (button?) to mark a sequence as read-only. Admins should be able to change sequences to/from read-only, and users should not be able to edit sequences marked as read-only.

The heavy-handed solution to this issue is a proper version control and permissions management systems in Phoenix, but this option is a lightweight solution that at least gives users some way to change control their sequence in the short term.