revisit group id management

[sripwoud]

Is your feature request related to a problem? Please describe.
The way the group id is generated (depends on the name) prevents allowing for updating the name (see #589).

Describe the solution you'd like
Why not stop generating groupIds on the application layer and let the db generate them instead (modify the groups table schema)?
A common practice is e.g to use an identity column. This way the unicity of the group id would be enforced at db level and you wouldn't have to worry about it. Especially it would break the dependency between name and groupId so we could allow updating the name

This is a breaking change (think about how to handle group id generated before/after the change)

[vplasencia]

Hey @sripwoud! Thanks for creating this issue. Yes, agree, the group ids should be automatically generated at db level.