frontend-tools: Display Python version in UI, suggest restart after version switch

[WizardCM]

Description

This adds a visual Python version in the UI to inform the user which version is currently, successfully loaded.

Additionally, if the user attempts to switch versions, a popup is shown to inform them that a restart is required.

~~I very much need help writing a better implementation of obs_scripting_python_version. I got tired of fighting it.~~

Motivation and Context

It can currently be very unclear to a user that a) Python loaded successfully and b) changing versions requires an OBS restart.

How Has This Been Tested?

• Set path to Python 3.8.10
• Change path to Python 3.10

Types of changes

• Tweak (non-breaking change to improve existing functionality)

Checklist:

• [x] My code has been run through clang-format.
• [x] I have read the contributing document.
• [x] My code is not on the master branch.
• [x] The code has been tested.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] I have included updates to all appropriate documentation.

[WizardCM]

Performed all changes requested in review. Ready for re-review.

[productdevbook]

linux dont see, how to change ubuntu ?