feat/vec export

[thlorenz]

Summary

This PR adds support for more return types for function exports via #[rid::export]. It contains some WIP for HashMap support as well. While working on that I realized that in order to send the keys() as a Vec it needs to be supported first.

Supported Types

I added lots of tests which verify that the following export return types are now supported:

Vecs

Vec<&struct>
Vec<&primitive>
Vec<&String>
Vec<&CString>
Vec<&str>

In the case of vecs with a string-like type the string value is not resolved until the item in the Vec is accessed in order to push out copying the data to convert to a *const char until the last possible moment.

Primitives

// owned
u8, i8, u16, i16 .. u64, i64
bool

// refererences
&u8, &i8, &u16, &i16 .. &u64, &i64
&bool

Strings

String, CString
&String, &CString, &str

They are sent as *const char to Dart.

C-Style Enums

Enums are converted to i8 when sent to Dart and serialized back into an enum on the Dart end.

Commits

• rid-macro: hash map prepared
• rid-macro: hash map rendering without access methods
• rid-macro: organizing vec dart render in separate dir
• rid-macro: renderable access trait and rendering hash map rust access
• deps: upgrade cbindgen to v0.20.0
• rid-macro: ref respected for return type
• rid-macro: fixed bool return type for exports
• rid-macro: fixed string returns from export
• rid-macro: using access type to distinguish return type render
• test: adding todo app integration test
• rid-macro: fix export Dart return type for enum
• test: adding export tests for current status
• rid-macro: export returning primitive refs
• rid-macro: export for string refs including as_str()
• rid-macro: fix numerous vec export issues
• rid-macro: rust_type::dart_wrapper_rust_ident now returns string
• rid-macro: vec to return type rendering
• rid-macro: export supporting Vec<&enum> return
• rid-macro: Vec<&String> via const char pointer
• rid-macro: adding access_string_ref to utils module
• rid-macro: removing snapshot assertions, covered by integration tests
• rid-macro: Vec<&String> exported via vec of pointers
• rid-macro: semi working Vec<&CString> solution
• rid-macro: simplifying access of Vec<&String|&CString>
• rid-macro: improved way to expose CString struct
• rid-macro: handling Vec<&str> exports