Add UTF-8 tests to RN

[janaakhterov]

Problem

We tests a wide variety of things already in the RN tests, but recently we discovered our RN utf8 implementation did not work. We should create tests for this to prevent it from happening again.

Solution

Create a test in RN that uses utf8 and confirms it works, e.g. use FileCreateTransaction where the value is passed in as a string, that should use our utf8 encoding to decoding the string and hence would confirm utf8 works as intended.

Alternatives

No response

[janaakhterov]

I think this needs to be moved to another sprint due to #1073