fix(env): Update method name parameters in env to string equivalents

[austinabell]

• Updates the function signatures from raw bytes for method names to String
  • These method names must be utf8 so this signature will be more ergonomic and harder to misuse.

Was related to something I was working on, and decided to break apart and PR separately

This is a breaking change, so could leave out of 4.0 release (#494) but I think this is incorrect and better to change sooner than later.

[mikedotexe]

Interesting, any idea why we would do this the other way in the first place?

[austinabell]

Interesting, any idea why we would do this the other way in the first place?

My guess, as similar from the log and panic signatures, that it was done cautiously to avoid any potential code size increases but this is not the case.

Also, going to think through alternatives and consider deprecating and creating a new function tomorrow morning, which is probably the better route than this breaking change.