feat: convert schedule.channel (char field) to schedule.slack_channel (foreign key) (#5199)
# What this PR does
`OnCallSchedule` equivalent of
https://github.com/grafana/oncall/pull/5191.
**NOTE**: merge after https://github.com/grafana/oncall/pull/5224 (so
that I can use some of the new serializer fields defined in there)
### Migration
```bash
Running migrations: │
│ source=engine:app google_trace_id=none logger=apps.schedules.migrations.0019_auto_20241021_1735 Starting migration to populate slack_channel field. │
│ source=engine:app google_trace_id=none logger=apps.schedules.migrations.0019_auto_20241021_1735 Total schedules to process: 1 │
│ source=engine:app google_trace_id=none logger=apps.schedules.migrations.0019_auto_20241021_1735 Schedule 26 updated with SlackChannel 2 (slack_id: C043LL6RTS7). │
│ source=engine:app google_trace_id=none logger=apps.schedules.migrations.0019_auto_20241021_1735 Bulk updated 1 OnCallSchedules with their Slack channel. │
│ source=engine:app google_trace_id=none logger=apps.schedules.migrations.0019_auto_20241021_1735 Finished migration. Total schedules processed: 1. Schedules updated: 1. Missing SlackChannels: 0. │
│ Applying schedules.0019_auto_20241021_1735... OK
```
### Tested Public API
```txt
POST {{oncall_host}}/api/v1/schedules/
Authorization: {{oncall_api_key}}
Content-Type: application/json
{
"name": "Demo testy testy2",
"type": "web",
"time_zone": "America/Los_Angeles",
"slack": {
"channel_id": "C05PPLYN1U1"
}
}
HTTP/1.1 201 Created
Content-Type: application/json
Vary: Accept, Origin
Allow: GET, POST, HEAD, OPTIONS
X-Frame-Options: DENY
Content-Length: 198
X-Content-Type-Options: nosniff
Referrer-Policy: same-origin
Cross-Origin-Opener-Policy: same-origin
{
"id": "SBBN73UTUTVCE",
"team_id": null,
"name": "Demo testy testy2",
"time_zone": "America/Los_Angeles",
"on_call_now": [],
"shifts": [],
"slack": {
"channel_id": "C05PPLYN1U1",
"user_group_id": null
},
"type": "web"
}
```
### Tested via UI (eg; internal API)
https://www.loom.com/share/e66bf3468b144dd782da5eb6e0bfd0af
## Checklist
- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
show up in the autogenerated release notes.
4a5c4263e0