Users: ignore case when diffing email and login

[IevaVasiljeva]

What

This PR makes user login and email diffing case insensitive.

Why

We've changed the implementation on Grafana's side to be case insensitive when resolving user emails and logins.

This already causes a diff for newly created users if upper case characters are used for user logins or emails, and will cause an even larger diff when grafana/grafana#86359 is merged, as we will be migrating all existing user logins and emails to lower case.

How to test

• use Grafana TF provider without this change;
• create a user with upper case characters in login/email;
• run terraform apply again and observe the diff;
• now use Grafana TF provider with this change and run terraform apply - no diff should appear.

User resource used:

resource "grafana_user" "test_user" {
  email    = "[email protected]"
  login    = "nEW_terRAForm_user"
  password = "password"
}

Diff observed:

  # grafana_user.test_user will be updated in-place
  ~ resource "grafana_user" "test_user" {
      ~ email    = "[email protected]" -> "[email protected]"
        id       = "15"
      ~ login    = "[email protected]" -> "[email protected]"
        # (3 unchanged attributes hidden)
    }

[github-actions]

In order to lower resource usage and have a faster runtime, PRs will not run Cloud tests automatically.
To do so, a Grafana Labs employee must trigger the cloud acceptance tests workflow manually.

[eleijonmarck]

could potentially add a case for all uppercase

only for all coverage

[IevaVasiljeva]

Oh, sorry, didn't see this comment before merging. I think in this case it doesn't matter enough to raise another PR just for that.