Search sharees on lookup server when explicitly requested by user

apps/files_sharing/js/additionalScripts.js

apps/files_sharing/js/additionalScripts.js.map

apps/files_sharing/lib/Controller/ShareesAPIController.php

apps/files_sharing/src/style/sharetabview.scss

...les_sharing/tests/Controller/ShareesAPIControllerTest.php

core/js/dist/share_backend.js

core/js/dist/share_backend.js.map

core/js/sharedialogview.js

core/js/tests/specs/sharedialogviewSpec.js

lib/private/Collaboration/Collaborators/LookupPlugin.php

tests/lib/Collaboration/Collaborators/LookupPluginTest.php