Heavy background jobs of other apps pause while a backup runs

Reserved in Nextcloud's job list, so no app is turned off and a job that is running goes on.
At most 6 hours in a row, then they get an hour; Nextcloud ends a reservation by itself after
12 hours, should the end of a pause never come. On by default, with a setting to turn it off.

src/api.js

@@ -34,6 +34,7 @@ export default {
 	setTargetLimit: (id, maxGb) => call('put', `/targets/${id}/limit`, { maxGb }),
 	startBackup: (targetId, label) => call('post', '/backups', { targetId, label }),
 	tick: () => call('post', '/tick'),
+	setPauseHeavyJobs: (enabled) => call('put', '/settings/pause-heavy-jobs', { enabled }),
 	setTargetSchedule: (id, schedule, timezone) => call('put', `/targets/${id}/schedule`, { schedule, timezone }),
 	snapshots: (targetId) => call('get', `/targets/${targetId}/snapshots`),
 	setSnapshotNote: (targetId, snapshotId, note) => call('put', `/targets/${targetId}/snapshots/${snapshotId}/note`, { note }),