Optionally avoid Keycloak requests in provider setup

[ltscif]

An extension of #89, this adds the option to disable initial login, defaulting to false. This will allow Keycloak itself to be provisioned via terraform and used as input to this provider.

Example:

data "helm_repository" "codecentric" {
  name = "codecentric"
  url  = "https://codecentric.github.io/helm-charts"
}

resource "helm_release" "keycloak" {
  repository = data.helm_repository.codecentric.metadata[0].name
  name       = "keycloak"
  namespace  = "keycloak"
  chart      = "keycloak"
  version    = "5.0.1"
}

resource "random_string" "keycloak_admin_password" {
  length  = 10
  special = false
}

provider "keycloak" {
  client_id     = "admin-cli"
  username      = "keycloak"
  password      = random_string.keycloak_admin_password.result
  url           = "http://keycloak.localhost"
  initial_login = false
}

resource "keycloak_realm" "realm" {
  depends_on = [helm_release.keycloak]
  realm  = "myrealm"
  enabled = true
}

[mrparkers]

Here are the differences I can see for the unhappy path when running this change locally:

with initial_login = true:

Error: Error refreshing state: 1 error(s) occurred:

* provider.keycloak: Post http://localhost:8080/auth/realms/master/protocol/openid-connect/token: dial tcp [::1]:8080: connect: connection refused

with initial_login = false:

keycloak_realm.test: Refreshing state... (ID: test)
keycloak_custom_user_federation.custom: Refreshing state... (ID: 7f7abf96-f377-43cc-9e23-5a3696c5df5c)

Error: Error refreshing state: 2 error(s) occurred:

* keycloak_realm.test: 1 error(s) occurred:

* keycloak_realm.test: keycloak_realm.test: error logging in: Post http://localhost:8080/auth/realms/master/protocol/openid-connect/token: dial tcp [::1]:8080: connect: connection refused
* keycloak_custom_user_federation.custom: 1 error(s) occurred:

* keycloak_custom_user_federation.custom: keycloak_custom_user_federation.custom: Get http://localhost:8080/auth/admin/realms/master/components/7f7abf96-f377-43cc-9e23-5a3696c5df5c: dial tcp [::1]:8080: connect: connection refused

While I still think that Terraform does not want providers to be configured with interpolated variables, I don't mind merging this since this is not a workflow that I personally use.