Editor GPU: Move decoration style parsing and validation into ViewGpuContext

[Tyriar]

This should move into ViewGpuContext so lines with inline decorations that aren't supported don't make it that far:

vscode/src/vs/editor/browser/gpu/fullFileRenderStrategy.ts

Lines 377 to 394 in 27687b2

	for (const rule of rules) {
	for (const r of rule.style) {
	const value = rule.styleMap.get(r)?.toString() ?? '';
	switch (r) {
	case 'color': {
	// TODO: This parsing and error handling should move into canRender so fallback
	// to DOM works
	const parsedColor = Color.Format.CSS.parse(value);
	if (!parsedColor) {
	throw new BugIndicatingError('Invalid color format ' + value);
	}
	charMetadata = parsedColor.toNumber24Bit();
	break;
	}
	default: throw new BugIndicatingError('Unexpected inline decoration style');
	}
	}
	}