wazero uses interfaces even when they aren't intended to be implemented
by users. We relied on documentation, to suggest what is implementable,
and in some cases documented correctly types that weren't for
implementation.
However, we didn't add that boilerplate to all types, and we also forgot
to recently when it was discussed a week or two ago. This finishes the
job by boilerplating all types that aren't for implementation. This also
orders to the top when it already existed.
Later, we can choose to enforce by type as well, we didn't know how to
do that before. Basically before we just casted to our internal types,
which would stop accidental implementation for things except people
using the types for wrapping purposes.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This adds a new top-level type FSConfig, which is configured via
`ModuleConfig.WithFSConfig(fcfg)`. This implements read-only and
read-write directory mounts, something not formally supported before. It
also implements `WithFS` which adapts a normal `fs.FS`. For convenience,
we retain the old `ModuleConfig.WithFS` signature so as to not affect
existing users much. A new configuration for our emerging raw
filesystem, `FSConfig.WithSysfs()` will happen later without breaking
this API.
Here's an example:
```
moduleConfig = wazero.NewModuleConfig().
// Make the current directory read-only accessible to the guest.
WithReadOnlyDirMount(".", "/")
// Make "/tmp/wasm" accessible to the guest as "/tmp".
WithDirMount("/tmp/wasm", "/tmp")
```
Signed-off-by: Adrian Cole <adrian@tetrate.io>
