Shuffle around the wiggle crates (#1414)

* Shuffle around the wiggle crates

This commit reorganizes the wiggle crates slightly by performing the
following transforms:

* The `crates/wiggle` crate, previously named `wiggle`, was moved to
  `crates/wiggle/crates/macro` and is renamed to `wiggle-macro`.

* The `crates/wiggle/crates/runtime` crate, previously named
  `wiggle-runtime`, was moved to `crates/wiggle` and is renamed to
  `wiggle`.

* The new `wiggle` crate depends on `wiggle-macro` and reexports the macro.

The goal here is that consumers only deal with the `wiggle` crate
itself. No more crates depend on `wiggle-runtime` and all dependencies
are entirely on just the `wiggle` crate.

* Remove the `crates/wiggle/crates` directory

Move everything into `crates/wiggle` directly, like `wasi-common`

* Add wiggle-macro to test-all script

* Fixup a test

crates/wiggle/generate/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "wiggle-generate"
+version = "0.13.0"
+authors = ["Pat Hickey <phickey@fastly.com>", "Jakub Konka <kubkon@jakubkonka.com>", "Alex Crichton <alex@alexcrichton.com>"]
+license = "Apache-2.0 WITH LLVM-exception"
+edition = "2018"
+description = "Library crate for wiggle code generator."
+categories = ["wasm"]
+keywords = ["webassembly", "wasm"]
+repository = "https://github.com/bytecodealliance/wasmtime"
+readme = "README.md"
+include = ["src/**/*", "LICENSE"]
+
+[lib]
+
+[dependencies]
+witx = { version = "0.8.4", path = "../../wasi-common/wig/WASI/tools/witx" }
+quote = "1.0"
+proc-macro2 = "1.0"
+heck = "0.3"
+anyhow = "1"
+syn = { version = "1.0", features = ["full"] }
+
+[badges]
+maintenance = { status = "actively-developed" }