feat: add endpoint for retrieving workspace acl (#19375)

Implements `/acl [get]` for workspaces, with tests.
Blocked by experiment enablement

coderd/database/queries/workspaces.sql

@@ -906,6 +906,15 @@ GROUP BY workspaces.id, workspaces.name, latest_build.job_status, latest_build.j
 -- name: GetWorkspacesByTemplateID :many
 SELECT * FROM workspaces WHERE template_id = $1 AND deleted = false;
 
+-- name: GetWorkspaceACLByID :one
+SELECT
+	group_acl as groups,
+	user_acl as users
+FROM
+	workspaces
+WHERE
+	id = @id;
+
 -- name: UpdateWorkspaceACLByID :exec
 UPDATE
 	workspaces