feat: Allow custom coloring of individual notation elements

[Danielku15]

Issues

Fixes #1769

Proposed changes

Introduces new model items to configure the coloring aspects of almost every notation element drawn by alphaTab. Effects are still grouped under one setting and cannot be colored individually.

If the feature is not configured, the performance is unchanged. Also if enabled it does not cost much.

Rendering colors.gp on develop
	Default 0 48.11279999999988
	Default 1 47.51969999999983
	Default 2 47.581500000000005
	Default 3 42.57079999999996
	Default 4 40.73900000000003
	Default 5 36.937400000000025
	Default 6 41.190399999999954
	Default 7 44.855999999999995
	Default 8 36.5958999999998
	Default 9 41.90910000000008

Rendering colors.gp on this branch with coloring disabled
	Default 0 49.2808
	Default 1 44.36830000000009
	Default 2 40.30169999999998
	Default 3 40.421100000000024
	Default 4 39.472999999999956
	Default 5 39.52059999999983
	Default 6 47.484300000000076
	Default 7 41.46129999999994
	Default 8 42.041999999999916
	Default 9 37.09280000000035

Rendering colors.gp on this branch with coloring enabled
	Colored 0 57.93299999999999
	Colored 1 46.3454999999999
	Colored 2 46.99189999999999
	Colored 3 42.432000000000016
	Colored 4 46.60509999999999
	Colored 5 41.88339999999994
	Colored 6 39.73289999999997
	Colored 7 40.97379999999998
	Colored 8 44.34050000000002
	Colored 9 41.152700000000095

Hence it should be safe to integrate.

Checklist

• I consent that this change becomes part of alphaTab under it's current or any future open source license
• Changes are implemented
• New tests were added

Further details

• This is a breaking change
• This change will require update of the documentation/website