Update Code Owners

[farmaazon]

Pull Request Description

• Removed Michał from owners' list.
• Removed old directories.
• Added Ad as owner of GUI, so it will be easier to accept urgent quickfixes.

Important Notes

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  TypeScript,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• Unit tests have been written where possible.

[AdRiley]

Perhaps shouldn't have things with no code owner. Can you add me, James, Pavel and Hubert for those ones?

[farmaazon]

Perhaps shouldn't have things with no code owner. Can you add me, James, Pavel and Hubert for those ones?

Even without owner, there is one accept needed. I just assumed it's ok to have no owner for shared files. But I can add them there, just I would add someone from GUI as well.

[jdunkerley]

Just a CODEOWNERs change.