[Sharing NG] Implement https://owncloud.dev/libre-graph-api/#/drives.permissions/GetPermission

[rhafer]

We're still lacking an implementation of

GET /v1beta1/drives/{driveid}/items/{itemid}/permissions/{permissionid}

[JammingBen]

According to https://owncloud.dev/libre-graph-api/#/drives.permissions/GetPermission we have this, can we close here?

[rhafer]

@JammingBen The spec is there. But the implementation is still missing :man_facepalming:

Same is true for GET /v1beta1/drives/{driveid}/root/permissions/{permissionid}

[JammingBen]

Ahh okay, so the well-known discrepancy again 😅