[Rust] Support convert utf16 encoded string to utf8 string

[chaokunyang]

Is your feature request related to a problem? Please describe.

Currently Fury xlang serialization use utf8 for string encoding, which is not performance efficient in many languages.

We introduced utf16 in https://fury.apache.org/docs/specification/fury_xlang_serialization_spec#string . But rust native string doesn't support utf16, it's is utf-8 encoded.

We should support to transcode utf16 encoded string to utf8 string in fury rust deserialization.

Describe the solution you'd like

Implement utf16 to utf8 convertion in fury rust. The implementation should use SIMD to provide faster speed.

Additional context

#1413