feat: Expose managed variables via API (#6134)

* WIP

* hcl

* useManagedVariables

* fix

* Fix

* Fix

* fix

* go:build

* Fix

* fix: bool flag

* Insert template variables

* API

* fix

* Expose via API

* More wiring

* CLI for testing purposes

* WIP

* Delete FIXME

* planVars

* WIP

* WIP

* UserVariableValues

* no dry run

* Dry run

* Done FIXME

* Fix

* Fix: CLI

* Fix: migration

* API tests

* Test info

* Tests

* More tests

* fix: lint

* Fix: authz

* Address PR comments

* Fix

* fix

* fix

coderd/database/migrations/migrate_test.go

@@ -241,6 +241,7 @@ func TestMigrateUpWithFixtures(t *testing.T) {
 		"replicas",
 		"template_version_parameters",
 		"workspace_build_parameters",
+		"template_version_variables",
 	}
 	s := &tableStats{s: make(map[string]int)}