Improve FileActions JS to allow for custom rendering

This improves the OCA.Files.FileActions class to support passing a
"render" function in the action object.

The default function "_defaultRenderFunction" is used by default and
renders actions in the usual actions container.

Moved "Rename" and "Delete" to custom render functions.
OCS API for server-to-server sharing
Check for working .htaccess via AJAX

Fixes https://github.com/owncloud/core/issues/12650
Merge pull request #12657 from owncloud/ajaxify-htaccess-check

Check for working .htaccess via AJAX
Remove unexisting `htAccessWorkinght`

Partially fixes https://github.com/owncloud/core/issues/12690 - remark to myself: improve grep skills.
Merge pull request #12394 from owncloud/files-fileactionsimprovements

Improve FileActions JS to allow for custom rendering
Merge pull request #12691 from owncloud/i-shall-improve-my-grep-skills

Remove unexisting `htAccessWorkinght`
Merge pull request #12452 from owncloud/server2server-ng-ocs

OCS API for server-to-server sharing
introduce alt text for rename icon - fixes #12067