Update Google Group Management on Guild Leader Change

[mkimberlin]

Depends on #2118

As an Admin,
I want the platform to automatically update the management role of the corresponding Google Group whenever I assign a new leader to a guild,
So that the new leader has the appropriate permissions to manage the Google Group for the guild.

Acceptance Criteria:

• If Google Group integration is enabled (see Associate Google Group with a Guild #2118):
  • When an Admin assigns a new leader to a guild:
    • The platform attempts to add the new leader to the corresponding Google Group as a Manager.
    • If the new leader is already a member of the group, update their role to Manager.
  • If the previous leader is still a member of the guild after the change:
    • The platform attempts to update their role in the corresponding Google Group to Member.
  • If the previous leader is completely removed from the guild:
    • The platform attempts to remove their email address from the corresponding Google Group.
  • If an error occurs while altering the membership of the Google Group:
    • The database is still updated to reflect the change in Guild membership.
    • The user receives an error notification detailing the issue with updating the Google Group. This notification should include the specific error message and the email address that failed to be added.