This patch updates the CLI to use anyhow and thiserror for error
management. The main feature that our custom `Error` type was providing
was a _list_ of messages, which would allow us to annotate "lower-level"
errors with more contextual information. This is exactly what's
provided by anyhow's `Context` trait.
(This is setup work for a future PR that will pull the `config` and
`loader` modules out into separate crates; by using `anyhow` we wouldn't
have to deal with a circular dependency between with the new crates.)
This is necessary on systems with SELinux to prevent file permission/access errors when building WASM output
* cli/src/wasm.rs: Use Z volume mount option for docker-run
* script/build-wasm: Likewise.
* Check that docker is on the PATH before trying to run it
* Don't try to use id(1) if using docker on windows
* Add error message if neither emcc nor docker are available
Fixes#358
