feat: add identity user data source and resource

[matejvelikonja]

This PR adds a new data resources ovh_me_identity_user and ovh_me_identity_users and a new resource ovh_me_identity_user.

Related OVH API: https://api.ovh.com/console/#/me/identity/user#GET

data "ovh_me_identity_user" "my_user" {
   user = "my_user_login"
}

data "ovh_me_identity_users" "users" {}

resource "ovh_me_identity_user" "my_user" {
   description = "Some custom description"
   email       = "my_login@example.com"
   group       = "DEFAULT"
   login       = "my_login"
   password    = "super-s3cr3t!password"
}

[pgaxatte]

Hello @matejvelikonja

Thank you for your awesome contribution!

We are actively reviewing this PR but the CI is currently not functioning (consequently to our move from the terraform-providers organization).
So we might merge this PR before finishing the fix of the CI (and some other stuff we have on our todo list) but we won't release until we have the CI running again.