Fix Removed Grants

[dehume]

If a grant is removed outside of Terraform, it would lead to an error in subsequent plan/applies rather than recreating the grant.

New Workflow

1. Grant via apply

resource "materialize_table_grant" "table_grant_insert" {
  role_name     = materialize_role.role_1.name
  privilege     = "INSERT"
  database_name = materialize_table.simple_table.database_name
  schema_name   = materialize_table.simple_table.schema_name
  table_name    = materialize_table.simple_table.name
}

2. Manually remove grant

REVOKE INSERT ON TABLE example_database.example_schema.simple_table FROM "role-1";

3. On next plan/apply

Terraform will perform the following actions:

  # materialize_table_grant.table_grant_insert will be created
  + resource "materialize_table_grant" "table_grant_insert" {
      + database_name = "example_database"
      + id            = (known after apply)
      + privilege     = "INSERT"
      + role_name     = "role-1"
      + schema_name   = "example_schema"
      + table_name    = "simple_table"
    }

Plan: 1 to add, 0 to change, 0 to destroy.

Fix applies to object, system and default grants

[benesch]

Code LGTM, but we should write a test for this, similar to how we test for objects disappearing:

terraform-provider-materialize/pkg/provider/acceptance_secret_test.go

Lines 74 to 98 in 7acc978

	func TestAccSecret_disappears(t *testing.T) {
	secretName := acctest.RandStringFromCharSet(10, acctest.CharSetAlpha)
	secret2Name := acctest.RandStringFromCharSet(10, acctest.CharSetAlpha)
	roleName := acctest.RandStringFromCharSet(10, acctest.CharSetAlpha)
	resource.ParallelTest(t, resource.TestCase{
	PreCheck: func() { testAccPreCheck(t) },
	ProviderFactories: testAccProviderFactories,
	CheckDestroy: testAccCheckAllSecretsDestroyed,
	Steps: []resource.TestStep{
	{
	Config: testAccSecretResource(roleName, secretName, "sekret", secret2Name, roleName),
	Check: resource.ComposeTestCheckFunc(
	testAccCheckSecretExists("materialize_secret.test"),
	testAccCheckObjectDisappears(
	materialize.ObjectSchemaStruct{
	ObjectType: "SECRET",
	Name: secretName,
	},
	),
	),
	ExpectNonEmptyPlan: true,
	},
	},
	})
	}