Introduce LLUIColorTable debug-settings-alike floater and fix various color system bugs

[RyeMutt]

• Introduce a floater that can access LLUIColortable and update/reset color settings
• Fix chat colors not dynamically updating when changed in preferences
• Fix script editors not dynamically updating when changed in script editor preferences
• Introduce alpha parameter to LLStyle to allow setting text UI color alpha at runtime without breaking reference to color table
• Cache and optimize various color finds during draw
  
  
  

[akleshchev]

This is undoubtfully a good change, but perhaps this should be in a different review? Adding alpha and background to text is a bit out of scope for a color debug floater.

[RyeMutt]

This was to replicate the previous behavior in https://github.com/secondlife/viewer/pull/2190/files#diff-b22849a085421bd71afc6b02046ac27f258e5c4ebc9c524b541653ab44174229L104 but without breaking the color reference and thus dynamic updates. I could try to separate out the bug fixes from the new floaterif that would be easier.

[akleshchev]

It's fine to keep it together if they are troublesome to separate. But please, separately note those alpha changes in review's header, just in case.

[akleshchev]

A lot of macOS build errors related to streams, like:

In file included from /Users/runner/work/viewer/viewer/indra/llcommon/llunits.h:31:
/Users/runner/work/viewer/viewer/indra/llcommon/llunittype.h:241:15: note: candidate template ignored: could not match 'LLUnit<type-parameter-0-0, type-parameter-0-1>' against 'LLUIColor'
std::ostream& operator <<(std::ostream& s, const LLUnit<STORAGE_TYPE, UNITS>& unit)
              ^

In file included from /Users/runner/work/viewer/viewer/indra/llrender/llrender.h:44:
/Users/runner/work/viewer/viewer/indra/llmath/llmatrix4a.h:263:22: note: candidate function not viable: no known conversion from 'LLUIColor' to 'const LLMatrix4a' for 2nd argument
inline std::ostream& operator<<(std::ostream& s, const LLMatrix4a& m)
                     ^

In file included from /Users/runner/work/viewer/viewer/indra/llmath/v4math.h:33:
/Users/runner/work/viewer/viewer/indra/llmath/v2math.h:434:22: note: candidate function not viable: no known conversion from 'LLUIColor' to 'const LLVector2' for 2nd argument
inline std::ostream& operator<<(std::ostream& s, const LLVector2 &a)
                     ^

[marchcat]

The build looks fine now.

Thank you for the contribution!