frontend: Add stay-on-top in the LogViewer window

[psyirius]

Description

Added an "Always on Top" checkbox to keep the Log Viewer on top at all times.

Motivation and Context

When diagnosing issues or developing/debugging obs or obs-plugins, we often open the Log Viewer checking for logs.
But there's no option to keep it on front to check logs in real-time.
This might not be an issue when using multiple monitors. But for single monitor it's been a hassle for real.

How Has This Been Tested?

• Launched OBS
• Opened Log Viewer
• Check "Always on Top"
• The window stays on top
• Persistence: ✅
• Build: ✅

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

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

[tytan652]

This feature needs to be excluded on Linux builds, with Wayland "Always on Top" can be no longer be decided by the application.

[psyirius]

This feature needs to be excluded on Linux builds, with Wayland "Always on Top" can be no longer be decided by the application.

Gotcha.
Following how OBS's always on top works.