Support changing labels of Actions runner without re-registration (#24806)

close #24540

related:
- Protocol: https://gitea.com/gitea/actions-proto-def/pulls/9
- Runner side: https://gitea.com/gitea/act_runner/pulls/201

changes:
- Add column of `labels` to table `action_runner`, and combine the value
of `agent_labels` and `custom_labels` column to `labels` column.
- Store `labels` when registering `act_runner`.
- Update `labels` when `act_runner` starting and calling `Declare`.
- Users cannot modify the `custom labels` in edit page any more.

other changes:
- Store `version` when registering `act_runner`.
- If runner is latest version, parse version from `Declare`. But older
version runner still parse version from request header.

routers/web/repo/actions/actions.go

@@ -84,7 +84,6 @@ func List(ctx *context.Context) {
 		allRunnerLabels := make(container.Set[string])
 		for _, r := range runners {
 			allRunnerLabels.AddMultiple(r.AgentLabels...)
-			allRunnerLabels.AddMultiple(r.CustomLabels...)
 		}
 
 		workflows = make([]Workflow, 0, len(entries))