refactor: Unify substream actions into substream_{on,off} (#2497)

## Summary

- Collapse `live_substream_{on,off,select}` into a unified
`substream_{on,off}` pair, symmetric with `call_{start,end}`.
- Rename the `camera` field on the former `live_substream_select` to
`stream` (it always was a stream ID).
- Add optional `camera` field to both new actions for targeting a
non-selected base camera.
- YAML configs are migrated automatically; URL bookmarks must be updated
by hand.

## Migration

### Cycling between camera and substream (toggle button)

Before:
```yaml
tap_action:
  action: custom:advanced-camera-card-action
  advanced_camera_card_action: live_substream_on
```

After:
```yaml
tap_action:
  action: custom:advanced-camera-card-action
  advanced_camera_card_action: substream_on
```

### Selecting a specific substream

Before:
```yaml
tap_action:
  action: custom:advanced-camera-card-action
  advanced_camera_card_action: live_substream_select
  camera: camera.front_door_hd
```

After:
```yaml
tap_action:
  action: custom:advanced-camera-card-action
  advanced_camera_card_action: substream_on
  stream: camera.front_door_hd
```

### Turning the substream off

Before:
```yaml
tap_action:
  action: custom:advanced-camera-card-action
  advanced_camera_card_action: live_substream_off
```

After:
```yaml
tap_action:
  action: custom:advanced-camera-card-action
  advanced_camera_card_action: substream_off
```

### URL querystrings (manual update required)

| Before | After |
| --- | --- |
|
`?advanced-camera-card-action.live_substream_select=camera.front_door_hd`
| `?advanced-camera-card-action.substream_on=camera.front_door_hd` |

tests/card-controller/lock/manager.test.ts

@@ -7,6 +7,8 @@ import {
   createGeneralAction,
   createLogAction,
   createMediaPlayerAction,
+  createSubstreamOffAction,
+  createSubstreamOnAction,
   createViewAction,
 } from '../../../src/utils/action';
 import { createCardAPI, createConfig } from '../../test-utils';
@@ -77,10 +79,10 @@ describe('LockManager', () => {
 
     for (const action of [
       createViewAction('clips'),
-      createCameraAction('camera_select', 'cam-1'),
-      createCameraAction('live_substream_select', 'cam-1'),
-      createGeneralAction('live_substream_on'),
-      createGeneralAction('live_substream_off'),
+      createCameraAction('cam-1'),
+      createSubstreamOnAction({ stream: 'cam-1' }),
+      createSubstreamOnAction(),
+      createSubstreamOffAction(),
       createGeneralAction('default'),
       createGeneralAction('pause'),
       createGeneralAction('reload'),