COMMON: Add String::forEachLine and convertBiDiStringByLines

[ZvikaZ]

convertBiDiStringByLines calls the BiDi algo for each line in isolation, and returns a joined result.
That's needed to support BiDi in AGI, and might be needed for other engines in the future.

In order to do that, a new utility function was added:
String::forEachLine which gets a function as input, and its arg(s) (if it has any), and calls the function on each line, and returns a new string which is all concatenation of all the lines results (with '\n' added between them).

[ccawley2011]

Have you looked at Common::StringTokenizer? It seems to do the same thing that Common::String::forEachLine does.

[ZvikaZ]

Well, I wasn't aware of Common::StringTokenizer's existence.

However, I have checked it now, and indeed, it's a handy function, but not equivalent to String::forEachLine.
We can think of Common::StringTokenizer as split in Python, while String::forEachLine does split, map and join in one function.

Therefore, the succinct

Common::String bidiByLineHelper(Common::String line, va_list args) {
	Common::Language lang = va_arg(args, Common::Language);
	return Common::convertBiDiString(line, lang);
}


String convertBiDiStringByLines(const String &input, const Common::Language lang) {
	return input.forEachLine(bidiByLineHelper, lang);
}

in this PR would be longer, had I used Common::StringTokenizer, as I had to write a loop that calls the tokenizer, and combines back the lines, and also taking care not to add \n at the end of the string.

[ZvikaZ]

BTW, another example of forEachLine usage is in changes I'm making now for AGI engine to support Hebrew. It needs to right align multi line strings. It's easily done with:

Common::String rightAlign(Common::String line, va_list args) {
	uint width = va_arg(args, uint);
	while (line.size() < width)
		line = " " + line;
	return line;
}
...
    textString = textString.forEachLine(rightAlign, (uint)_messageState.textSize_Width);