Review resource permission checks

Review the following resources, they might either use too broad a permission check, or lack one entirely.

- [ ] [Lookup Tables](https://github.com/Graylog2/graylog2-server/blob/master/graylog2-server/src/main/java/org/graylog2/rest/resources/system/lookup/LookupTableResource.java#L108)
- [ ] potentially unused [StatsResource](https://github.com/Graylog2/graylog2-server/blob/master/graylog2-server/src/main/java/org/graylog2/rest/resources/system/StatsResource.java#L43)
- [ ] potentially unused [ServiceManagerResource](https://github.com/Graylog2/graylog2-server/blob/8ce9b3f5323b52e43c59c26777688015236d4ef9/graylog2-server/src/main/java/org/graylog2/rest/resources/system/jobs/ServiceManagerResource.java#L51)
- [ ] is this ever used unauthenticaed? [PermissionsResource#readerPermissions](https://github.com/Graylog2/graylog2-server/blob/7a289b173f63756ed8969970ea90f3fd46befabe/graylog2-server/src/main/java/org/graylog2/rest/resources/system/PermissionsResource.java#L76)
- [ ] might need a new permission for granular access [OutputResource#available](https://github.com/Graylog2/graylog2-server/blob/ee419553918d1d3c3247e470f435ac0f270b9c22/graylog2-server/src/main/java/org/graylog2/rest/resources/system/outputs/OutputResource.java#L184)
- [ ] [ReportingConfigResource#read](https://github.com/Graylog2/graylog-plugin-enterprise/pull/11097/files#diff-b911a7569edaba52ae723fbae12c3318eb6cc18b9e5f9f1503525dbe56b2087e)