[lib] Disable edit button when link secret isn't changed

Summary:
Enable the button only after the link is changed.

https://linear.app/comm/issue/ENG-7149/edit-link-button-is-active-when-a-link-wasnt-changed

Depends on D11269

Test Plan: Open manage links screen on web and native - the button should be disabled. Change the link - the button should become enabled.

Reviewers: inka, atul

Reviewed By: inka

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11270