Enhancement: Improve performance when loading folders and share indicators

The performance when loading folders and share indicators has been improved by optimizing the way how shares are being loaded.

https://github.com/owncloud/web/issues/7721
https://github.com/owncloud/web/pull/8349
https://github.com/owncloud/web/pull/8482
https://github.com/owncloud/web/pull/8667
https://github.com/owncloud/web/pull/8915
