Show user display name on external share confirmation dialog

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Is your feature request related to a problem? Please describe.
When receiving a remote share from another server, the username show to the user is the Nextcloud login/ID.
This happens even with a trusted server or a known user (from contacts/lookup server).
This can be complicated to read when using user backend like LDAP, the login/ID is a UUID by default.

An example :

Describe the solution you'd like
When a remote share is received, Nextcloud should use a known display name (contacts, trusted servers, lookup server, etc…).
This aims to mimic the behavior of the share tab on the file informations with a remote share, this show the known display name.

The same share after being accepted in the said share tab :

Describe alternatives you've considered
Change the Nextcloud login name in the LDAP backend expert parameters.
This can create collision between user and need to recreate all accounts from scratch.

Start by locating the external share confirmation dialog and the existing display-name handling used in the file information share tab. Trace how remote-share identities are resolved from contacts, trusted servers, or the lookup server. Done means the confirmation dialog shows the known display name when available while retaining a usable fallback.