Crisp scaling overlay support + startup visibility as a project setting

[antzGames]

Implements: #27 and #18

Here is a brief overview of features implemented:

• Crisp font based scaling of overlay.
• Includes proper scaling of Graphs, Header Widths, Line Spacing, and Font Outline Size.
• A font size can now be set via a Project Setting OR by calling DebugMenu.set_font_size() in code.
• The default font size is 12, which means it will look exactly like it is today.
• F4 key cycles through predefined font sizes, including the user's set font size (from above) - Predefined font sizes are, 3, 6, 12, 18, 24, 30. F4 key is only active when DebugMenu is visible.
• Supported font size is from 3-72, which should accommodate very small viewports+streched_mode=canvas , and very large 4k viewports with stretch_mode=disabled.

ALSO:
You can now set the startup visibility (hidden, visible_compact, visible_detailed) in the Project Settings. Default is hidden.

Testing:

• Tested on Windows desktop and/or Web build on multiple projects, mostly Compatibility renderer.
• Tested ONLY with built in system font. Other fonts might introduce header width issues.

[antzGames]

I understand you are very busy, and its best you focus on Godot engine specific work.

Cleaning up my fork so I can include even more features. Cheers.

https://github.com/antzGames/Antz-Debug-Menu