#579 "Add user to group" only works for the first group listed on My Account > Groups page

[Nirattiya Jaisieng]

Summary:
On the My Account > Groups page, when a user is a manager of more than one group, the "Add user to group" dropdown only works for the first group in the list. Selecting a user in the dropdown for any subsequent group does nothing — no error, no page reload, no JS console error.

Steps to reproduce:

1. Log in as a user who is manager of 2 or more groups.
2. Go to My Account > Groups.
3. In the first listed group, use "Add user to group" dropdown — works as expected.
4. In the second (or later) listed group, use "Add user to group" dropdown and select a user — nothing happens.

Version of SeedDMS 6.0.40

[Uwe Steinmann]

The javascript was simply not capable of handling more than one 'Add user' form. This will be fixed in 5.1.48 and 6.0.41