winch: Adding support for integration tests (#5588)

* 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

winch/filetests/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+authors = ["The Winch Project Developers"]
+name = "winch-filetests"
+description = "Tests for the Winch compiler based on a set of known valid files"
+license = "Apache-2.0 WITH LLVM-exception"
+repository = "https://github.com/bytecodealliance/wasmtime"
+version = "0.0.0"
+publish = false
+edition.workspace = true
+
+[dependencies]
+winch-test-macros = {workspace = true}
+target-lexicon = { workspace = true }
+winch-codegen = { workspace = true, features = ['all-arch'] }
+wasmtime-environ = { workspace = true }
+anyhow = { workspace = true }
+wat = { workspace = true }
+similar = { workspace = true }
+toml = { workspace = true }
+serde = { workspace = true }
+cranelift-codegen = { workspace = true }
+capstone = { workspace = true }