[Gimp-web] Updating references to Bugzilla

All,

I'm in the process of updating pages on the website that reference
Bugzilla. (per the issue here:
https://gitlab.gnome.org/Infrastructure/gimp-web/issues/1)

Unless I hear otherwise, my thoughts are:

* Update all references from "Bugzilla" to "GitLab issues".
* Change the link on /bugs/ for "How To Report an Issue" from
/bugs/howtos/bugzilla.html to /bugs/report.html
* Change link on /bugs/ for "How To Create and Submit a Patch" from
/bugs/howtos/submit-patch.html to /bugs/submit-patch.html
* Update the previous two referenced pages content to reflect "GitLab
issues" rather than "Bugzilla".
* Add new text at the top of those same two pages to notify users the pages
are deprecated, and link to the new locations.

I'll leave the old pages in-place, but we may want to redirect (302) to the
new location at some point.

Any thoughts on these?

pat
-- 
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