feat: Add Char.byteCount

[spotandjake]

This adds Char.byteCount which can be used with a specified encoding to get the encoded length of a char.

Example use case for this is stepping through a byte array when you do Byte.getChar you have no clue how far to advance for the next char without this.

[ospencer]

This would need to be called utf8EncodedLength or something like that to be specific about what byte length it's referring to.

[spotandjake]

This would need to be called utf8EncodedLength or something like that to be specific about what byte length it's referring to.

The function takes an encoding parameter and will return the byte count in the specified encoding. It takes the same encodings as our String.encode and String.decode functions.

[alex-snezhko]

Can check this at the beginning since it'll always be 4 but nbd

[spotandjake]

I don't think it's worth it as it makes the match non exhaustive and adds an extra branch, UTF32 probably isn't going to be used very often anyways so optimizing for it doesn't seem worth it.