Update references to adblockplusui GitLab project

Background / User story

We recently renamed the adblockplusui GitLab project to adblockplus, so we should update any references to adblockplusui in the codebase.

What to change

• Design: N/A
• Research: N/A
• Spec: N/A
• Legal: N/A
• Development: Replace any references to https://gitlab.com/adblockinc/ext/adblockplus/adblockplusui (or https://gitlab.com/eyeo/adblockplus/abpui/adblockplusui) with https://gitlab.com/adblockinc/ext/adblockplus/adblockplus.

Hints for testers

Apart from minor meta data changes in package.json, these are solely changes to documentation and comments.

Hints for translators

N/A