SVG & PNG for color LCD radio - change & clean up

[JimB40]

This PR

• integrates Figma as source for SVG graphics
• automated PNG build for color LCD radios via covert-gfx.sh

Summary of changes:

1. changed img-src files names & folder structure

• files follows naming <bmp_|mask_><type_>.svg scheme that follows Figma UI Design scheme
• bmp_ & mask_ prefix defines PNG type
• no subfolders to simplify PNG generation & review
• all SVG vector sources simplified end re-exported to img-src

2. Replaced PNG

• PNGs now have new names
• unused PNGs are removed
• conversion done using rsvg-convert for smaller size

3. Modified CMakeList.txt

• simplified

4. Modified *.cpp

• all *.cpp with *.lbm references are updated to reflect naming change
• _BuiltinIcon names left untouched to avoid conflicts (lots of changes in code)

5. tools script to convert SVG to PNG

• changed script name to convert-gfx.sh
• added --resvg param to force using resvg insted of rsvg-convert (testing)

Other PRs @pfeerick

• this affects #6753 so probably this one should be merged first ?
• will close #6779
• may close #6772 :)

[JimB40]

Figma Integration

• left > Design window
• right > Export SVG window

Any changes in Design window are automatically refleced in Export SVG window that converts graphic to specified type (normal PNG or mask PNG)