Move users/databases to for_each

[Dev25]

^
Closes #96

Noticed a couple of object fields instance and project were never used so also removed them

To consider

• Merge users and additonal_users + same for databases, seems a bit pointless having them seperate and since we've already done a breaking API change might as well merge them now.
• Move read_replicas to for_each

[bharathkkb]

Overall LGTM
Regarding points to consider, I havent used this module much but
Arent read_replicas defined under /modules/[mysql/pgsql]/read_replica.tf already using for_each

[Dev25]

Arent read_replicas defined under /modules/[mysql/pgsql]/read_replica.tf already using for_each

The replica configuration blocks are done via for_each but not the instance resource

resource "google_sql_database_instance" "replicas" {
  count                = var.read_replica_size

[Dev25]

I think for now lets ignore read replicas, imo that entire section could be more flexible e.g. different instance tiers/settings for different replicas so if/whenever that changes we could move to for_each then as well.

[syedrakib]

Do we have any ETA on this?

[bharathkkb]

@Dev25 we have a conflict, can you rebase ?
@morgante PTAL

[morgante]

Thank you and sorry for the delay.