Bugfix: File list render performance

We've drastically increased the initial render performance of the files list by removing the lazy loading delay and by moving the loading visualization from the OcTd to the OcTr component. For the selection of files there also has been a slight improvement in render speed.

https://github.com/owncloud/web/issues/7038
https://github.com/owncloud/web/pull/7298
https://github.com/owncloud/web/pull/7312
https://github.com/owncloud/web/pull/7367
