Reuse the previous invite code when updating an invitation

[rdimitrov]

Summary

The following PR reuses the previous invite code when updating an invitation. This would allow for older invitations to still work. The initial email content may not reflect the new state, but we are okay with this (synced with Evan) there'll be a follow up email being send in case the role changed

• Waiting for confirmation from @ethomson in case we don't want this behavior.

Change Type

Mark the type of change your PR introduces:

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

Outline how the changes were tested, including steps to reproduce and any relevant configurations.
Attach screenshots if helpful.

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 52.53% (+0.03%) from 52.5%
when pulling 89935e6 on reuse-code
into 6cc166f on main.

[coveralls]

coverage: 52.473% (+0.04%) from 52.438%
when pulling d898137 on reuse-code
into 37323cd on main.

[ethomson]

The initial email content may not reflect the new state

Okay, so -- what happens is:

• admin invites user with role x
• user gets email telling them that they were invited with role x, and an invite link
• admin updates user's role to y
• user gets another email telling them that that they were invited with role y, and (the same) invite link

I think that's great,