Add method for reading C-style strings from WasmPtr

[MarkMcCaskey]

Suggested on spectrum .

This is a very good idea, we should support getting a slice from a null-terminated array and probably have a function that just returns a &str too. Edge cases to watch out for are null bytes in UTF-8 may be valid if in code point. If that is the case, then we'll want to have a helper method specifically for reading UTF-8 from a WasmPtr with a null terminator. ASCII can probably go through CStr

[srenatus]

Edge cases to watch out for are null bytes in UTF-8 may be valid if in code point.

From searching the internet, I've come to believe that the only valid code point containing null is null. If that is correct, I don't see how we should differentiate the terminating null from a "non terminating" one. The only way to get an utf8 string from wasm memory that may contain null is the existing one, knowing offset and length.

Am I missing something?

Happy to take a stab at this, but can't make promises wrt. time ;)