Enable page sharing

Summary:
Use the new ShareUrl support from Purpose to share pages. ATM only sending the page via KDE Connect and Email is supported, but more can be added easily by extending Purpose.

Depends on D17285
Bug: 393543

Test Plan: Send page to phone via KDE Connect

Reviewers: Falkon, drosca

Reviewed By: Falkon, drosca

Subscribers: drosca, falkon

Tags: Falkon

Differential Revision: https://phabricator.kde.org/D17286