Add documentation and refactor wasmtime-wasi (#8228)

* Add documentation and examples for `wasmtime-wasi`

This commit adds lots of missing documentation and examples to top-level
types in `wasmtime-wasi`, mostly related to WASIp2. I've additionally
made a number of small refactorings here to try to make the APIs a bit
more straightforward and symmetric and simplify where I can.

* Remove `bindings::wasi` (reexports are still present under `bindings`)
* Rename `bindings::sync_io` to `bindings::sync`
* Generate fewer bindings in `bindings::sync` that can be pulled in from
  the `bindings` module.
* Change `WasiCtxBuilder::preopened_dir` to take a path instead of a
  `Dir` argument to avoid the need for another import.
* Synchronize `wasmtime_wasi_http::{add_to_linker, sync::add_to_linker}`
  in terms of interfaces added.
* Remove `wasmtime_wasi::command` and move the generated types to the
  `bindings` module.
* Move top-level add-to-linker functions to
  `wasmtime_wasi::add_to_linker_sync` and
  `wasmtime_wasi::add_to_linker_async`.

Closes #8187
Closes #8188

* Add documentation for `wasmtime_wasi::preview1` and refactor

This commit adds documentation for the `wasmtime_wasi::preview1` module
and additionally refactors it as well. Previously this was based on a
similar design as WASIp2 with a "view trait" and various bits and
pieces, but the design constraints of WASIp1 lends itself to a simpler
solution of "just" passing around `WasiP1Ctx` instead. This goes back to
what `wasi-common` did of sorts where the `add_to_linker_*` functions
only need a projection from `&mut T` to `&mut WasiP1Ctx`, a concrete
type, which simplifies the module and usage.

* Small refactorings to `preopened_dir`

* Add `WasiCtx::builder`.

* Fix typo

* Review comments

crates/wasi-http/src/proxy.rs

@@ -12,7 +12,7 @@ wasmtime::component::bindgen!({
 
 pub fn add_to_linker<T>(l: &mut wasmtime::component::Linker<T>) -> anyhow::Result<()>
 where
-    T: WasiHttpView + wasmtime_wasi::WasiView + bindings::http::types::Host,
+    T: WasiHttpView + wasmtime_wasi::WasiView,
 {
     wasmtime_wasi::bindings::clocks::wall_clock::add_to_linker(l, |t| t)?;
     wasmtime_wasi::bindings::clocks::monotonic_clock::add_to_linker(l, |t| t)?;
@@ -47,18 +47,24 @@ pub mod sync {
         async: false,
         with: {
             "wasi:http": bindings::http, // http is in this crate
-            "wasi:io": wasmtime_wasi::bindings::sync_io, // io is sync
+            "wasi:io": wasmtime_wasi::bindings::sync, // io is sync
             "wasi": wasmtime_wasi::bindings, // everything else
         },
     });
 
     pub fn add_to_linker<T>(l: &mut wasmtime::component::Linker<T>) -> anyhow::Result<()>
     where
-        T: WasiHttpView + wasmtime_wasi::WasiView + bindings::http::types::Host,
+        T: WasiHttpView + wasmtime_wasi::WasiView,
     {
-        // TODO: this shouldn't be required, but the adapter unconditionally pulls in all of these
-        // dependencies.
-        wasmtime_wasi::command::sync::add_to_linker(l)?;
+        wasmtime_wasi::bindings::clocks::wall_clock::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::clocks::monotonic_clock::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::sync::io::poll::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::sync::io::streams::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::io::error::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::cli::stdin::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::cli::stdout::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::cli::stderr::add_to_linker(l, |t| t)?;
+        wasmtime_wasi::bindings::random::random::add_to_linker(l, |t| t)?;
 
         add_only_http_to_linker(l)?;
 

crates/wasi-http/tests/all/async_.rs

@@ -1,6 +1,6 @@
 use super::*;
 use test_programs_artifacts::*;
-use wasmtime_wasi::command::Command;
+use wasmtime_wasi::bindings::Command;
 
 foreach_http!(assert_test_exists);
 
@@ -13,7 +13,7 @@ async fn run(path: &str, server: &Server) -> Result<()> {
     let component = Component::from_file(&engine, path)?;
     let mut store = store(&engine, server);
     let mut linker = Linker::new(&engine);
-    wasmtime_wasi::command::add_to_linker(&mut linker)?;
+    wasmtime_wasi::add_to_linker_async(&mut linker)?;
     wasmtime_wasi_http::proxy::add_only_http_to_linker(&mut linker)?;
     let (command, _instance) = Command::instantiate_async(&mut store, &component, &linker).await?;
     let result = command.wasi_cli_run().call_run(&mut store).await?;

crates/wasi-http/tests/all/sync.rs

@@ -1,6 +1,6 @@
 use super::*;
 use test_programs_artifacts::*;
-use wasmtime_wasi::command::sync::Command;
+use wasmtime_wasi::bindings::sync::Command;
 
 foreach_http!(assert_test_exists);
 
@@ -12,7 +12,8 @@ fn run(path: &str, server: &Server) -> Result<()> {
     let component = Component::from_file(&engine, path)?;
     let mut store = store(&engine, server);
     let mut linker = Linker::new(&engine);
-    wasmtime_wasi_http::proxy::sync::add_to_linker(&mut linker)?;
+    wasmtime_wasi::add_to_linker_sync(&mut linker)?;
+    wasmtime_wasi_http::proxy::sync::add_only_http_to_linker(&mut linker)?;
     let (command, _instance) = Command::instantiate(&mut store, &component, &linker)?;
     let result = command.wasi_cli_run().call_run(&mut store)?;
     result.map_err(|()| anyhow::anyhow!("run returned an error"))