Wasmer run-unstable

[Michael-F-Bryan]

This implements a second version of the wasmer run command to make the flow easier to follow and use WEBC runners.

In particular, it...

• Introduces a wasmer run-unstable sub-command which will eventually replace wasmer run and add a bunch of integration tests for it
• Deprecates several feature flags in the CLI (cache, cache-blake3-pure, debug, wasi, emscripten, webc_runner), making sure their functionality is always included and the flags themselves are no-ops
• Introduces a wasmer_cli::WasmerHome abstraction for interacting with the $WASMER_DIR directory and our integrating it with our caches
• Introduces an impl<D> Filesystem for D where D: Deref<Target = impl Filesystem> so Box<dyn FileSystem> and friends implement the FileSystem trait
• fixes a bug in wasmer_vfs::WebcFileSystem where you would OOM or have an infinite loop because reads would never increment the file's cursor
• Propagate environment variables and mapped directories to the WASI runner
• Wire up logging and error-handling middleware to the server started by the WCGI runner

We're calling it wasmer run-unstable instead of overwriting the wasmer run command for now until we get a chance to do more testing.

Fixes #3514.