Summary:
On X several target atoms are established to provide data similar to the
text/uri-list target format (the respective MIME on Wayland is called
text/x-uri).

Firefox can send link data in the NETSCAPE_URL format ones. Chromium on the
other side sends link data in the text/x-moz-url format, which transports
UTF-16 text.

For both these peculiarities this patch provides converter functions, that
translate these formats into the Wayland native text/x-uri format. In the
other direction no translation is necessary. Both browsers supports the
text/uri-list format when receiving link lists.

Test Plan: Manually with Firefox and Chromium.

Reviewers: #kwin

Subscribers: zzag, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D15629