Add String::from_utf8_lossy and String::from_utf8

[zxch3n]

No description provided.

[Lampese]

Buffer::to_string() or Bytes::to_string?

[zxch3n]

@Lampese No, IMO they are too ambiguous.

For the Bytes b with the value of [65], what should be the output of b.to_string()?

• [65]
• A if we treat it as utf8
• Error if we treat it as utf16

[chawyehsu]

It would be better to support bidirectional conversion between UTFs instead of providing only one way interface. I remember this was requested elsewhere before. Edit: #484

[zxch3n]

@chawyehsu This provides the most intuitive API for converting UTF8 to a built-in String. What's the alternative API design for this?

[suiyunonghen]

I wrote an implementation：
https://github.com/suiyunonghen/moonvalue/blob/master/src/utf8.mbt