Add backend changes for continuous automations on policies (#45999)

Resolves #45149 and #45150.

- [X] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.

- [X] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements), JS
inline code is prevented especially for url redirects, and untrusted
data interpolated into shell scripts/commands is validated against shell
metacharacters.

## Testing

- [X] Added/updated automated tests
- [x] QA'd all new/changed functionality manually

## Database migrations

- [X] Checked schema for all modified table for columns that will
auto-update timestamps during migration.
- [X] Confirmed that updating the timestamps is acceptable, and will not
cause unwanted side effects.
- [X] Ensured the correct collation is explicitly set for character
columns (`COLLATE utf8mb4_unicode_ci`).

- [x] Verified that the setting is exported via `fleetctl
generate-gitops`
- [X] Verified the setting is documented in a separate PR to [the GitOps
documentation](https://github.com/fleetdm/fleet/blob/main/docs/Configuration/yaml-files.md#L485)
- [x] Verified that the setting is cleared on the server if it is not
supplied in a YAML file (or that it is documented as being optional)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added team policy setting continuous_automations_enabled (default:
false) to re-run software/script automations on every failing
evaluation; exposed in APIs and GitOps YAML. Disallowed for "All fleets"
and requires a premium license.

* **Tests**
* Added integration tests for CRUD, GitOps, and re-queuing behavior
validating continuous automations.

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server/webhooks/failing_policies_test.go

@@ -129,6 +129,7 @@ func TestTriggerFailingPoliciesWebhookBasic(t *testing.T) {
 		"critical": true,
 		"calendar_events_enabled": false,
 		"conditional_access_enabled": false,
+		"continuous_automations_enabled": false,
 		"type": "dynamic"
     },
     "hosts": [
@@ -322,6 +323,7 @@ func TestTriggerFailingPoliciesWebhookTeam(t *testing.T) {
 		"critical": false,
 		"calendar_events_enabled": true,
 		"conditional_access_enabled": false,
+		"continuous_automations_enabled": false,
 		"type": "dynamic"
     },
     "hosts": [