TypeScript Non-Ascii encodings

[pouya-eghbali]

In our TypeScript generator, we throw if encoding is not ascii, see:

sia-schema/src/generator/ts/index.ts

Lines 267 to 274 in 703e1c7

	private getSerializeFunctionName(field: FieldDefinition): string {
	if (field.type === "string") {
	if (field.encoding === "ascii") {
	return "sia.addAscii";
	}
	throw new Error(`Unknown encoding: ${field.encoding}`);
	}

If encoding is not specified or is anything other than ascii, we should use one of sia.addString{N|8|16|32|64}. I also noticed we are using string type, which is incorrect. It should be string{8|16|32|64}. I checked and string{N|8|16|32|64} is valid. @Hamedblue1381, check and make sure string is not a valid type anymore, and make sure the TypeScript generator works with any other encoding.