gnu: webkitgtk: Patch to share store via Bubblewrap.

Fixes <https://bugs.gnu.org/40837

>.

* gnu/packages/patches/webkitgtk-share-store.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/webkit.scm (webkitgtk)[source](patches): Use it.

Co-authored-by: Marius Bakke <mbakke@fastmail.com>