Editor GPU: Ignore token foreground color when there is a decoration with a foreground color

[Tyriar]

With #234127 there is a new charMetadata that is passed along to the rasterizer and used as a key for the glyph:

vscode/src/vs/editor/browser/gpu/raster/glyphRasterizer.ts

Lines 120 to 124 in 9088a37

	if (charMetadata) {
	this._ctx.fillStyle = `#${charMetadata.toString(16).padStart(8, '0')}`;
	} else {
	this._ctx.fillStyle = colorMap[TokenMetadata.getForeground(metadata)];
	}

vscode/src/vs/editor/browser/gpu/atlas/textureAtlasPage.ts

Line 92 in 9088a37

this._glyphMap.set(chars, tokenMetadata, charMetadata, rasterizer.cacheKey, glyph);

A problem with this immediately is that the tokenMetadata's color becomes redundant as it's foreground color is overridden by charMetadata (inline decorations). Meaning for different tokens with the same decoration, or even just same decoration color, the glyph will be duplicated in the atlas.

I think the best way forward here is to delete the portion of tokenMetadata if there is a decoration foreground color, similar to what we do here:

vscode/src/vs/editor/browser/gpu/atlas/textureAtlas.ts

Lines 109 to 110 in 9088a37

	// Ignore metadata that doesn't affect the glyph
	tokenMetadata &= ~(MetadataConsts.LANGUAGEID_MASK | MetadataConsts.TOKEN_TYPE_MASK | MetadataConsts.BALANCED_BRACKETS_MASK);

Note that I think this also applies to partially transparent colors as it replaces the original color, not layers on top of it.