Improve user share suggestions

[nickvergessen]

• Entering the email of a local user should bring up the user as a local share
• Entering the cloud id of a local user should bring up the user as a local share
• Searching for Bj Schi should bring up Björn Schi as well (space as a "and"-separator for better results)

As discussed @schiessle

[kinimodmeyer]

sorry for referencing the issue (twice). i will add pull request to care for the two remaining points here.

[pierreozoux]

As a user of a global scale setup, I'm not aware that other users are on a different instance.

As an admin, I'd like to have an option to "hide" the fact that other users are on different instances.

This would result in the suggestion showing remote users as local users.

In term of implementation, I'd see something like this:

• add a toggle in admin>share section to present "users" from other trusted servers, as local users (hiding the cloud id part of the user) (it is then the responsibility of the admin to be sure that there is no overlap between userids between the 2, and if there is an overlapp, the UI shows 2 users which look like identical, sorry)
• if the toggle is on, then the UI would hide the cloud id and present the remote user as a local user.