This commit introduces the `winch-environ` crate. This crate's responsibility is
to provide a shared implementatation of the `winch_codegen::FuncEnv` trait,
which is Winch's function compilation environment, used to resolve module and
runtime specific information needed by the code generation, such as resolving
all the details about a callee in a WebAssembly module, or resolving specific
information from the `VMContext`.
As of this change, the implementation only includes the necessary pieces to
resolve a function callee in a WebAssembly module. The idea is to evolve the
`winch_codegen::FuncEnv` trait as we evolve Winch's code generation.
* Adding in the foundations for Winch `filetests`
This commit adds two new crates into the Winch workspace:
`filetests` and `test-macros`. The intent is to mimic the
structure of Cranelift `filetests`, but in a simpler way.
* Updates to documentation
This commits adds a high level document to outline how to test Winch
through the `winch-tools` utility. It also updates some inline
documentation which gets propagated to the CLI.
* Updating test-macro to use a glob instead of only a flat directory
