Refactors theming app - part 3

[fsamapoor]

Summary

Following previous PRs taking advantage of PHP8's constructor property promotion, I have also made the required adjustments to the classes in the theming app.

I decided to split the changes into multiple PRs to make reviewing the changes easier.

The improvements in this PR include:

• Using PHP8's constructor property promotion
• Adding return types
• Removing redundant docblocks

Checklist

• Code is properly formatted
• Sign-off message is added to all commits

[github-actions]

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[skjnldsv]

Hey @fsamapoor closing, there's too much conflicts and/or changes got applied already via another PR.
But I'd like to personally thank you again for all the other PRs we were able to merge.

We're slowly deploying rector that should help us continuing the refactoring on the long run! Have a lovely day!!

[fsamapoor]

@skjnldsv Hello John, thanks for the comment. No problem at all. I'm happy that I was able to contribute to the project! 🙌🏼