* Add an integration test for relative imports on SimpleModuleLoader
* Add a path to Module (and expose it in Referrer)
This allows SimpleModuleLoader to resolve relative to the current
file (which this commit also does).
Fixes#3782
* cargo clippy and fmt
* prettier
* Fix merge error
* `Context` independent `CodeBlock`s
This allows us to share `CodeBlock`s between `Context`, which makes
functions sharable between `Context`s.
* Apply review