extension: Add capabilities for the process API (#26224)

This PR adds support for capabilities for the extension process API.

In order to use the process API, an extension must declare which
commands it wants to use, with arguments:

```toml
[[capabilities]]
kind = "process:exec"
command = "echo"
args = ["hello!"]
```

A `*` can be used to denote a single wildcard in the argument list:

```toml
[[capabilities]]
kind = "process:exec"
command = "echo"
args = ["*"]
```

And `**` can be used to denote a wildcard for the remaining arguments:

```toml
[[capabilities]]
kind = "process:exec"
command = "ls"
args = ["-a", "**"]
```

Release Notes:

- N/A

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/extension_host/src/extension_store_test.rs

@@ -163,6 +163,7 @@ async fn test_extension_store(cx: &mut TestAppContext) {
                         slash_commands: BTreeMap::default(),
                         indexed_docs_providers: BTreeMap::default(),
                         snippets: None,
+                        capabilities: Vec::new(),
                     }),
                     dev: false,
                 },
@@ -191,6 +192,7 @@ async fn test_extension_store(cx: &mut TestAppContext) {
                         slash_commands: BTreeMap::default(),
                         indexed_docs_providers: BTreeMap::default(),
                         snippets: None,
+                        capabilities: Vec::new(),
                     }),
                     dev: false,
                 },
@@ -356,6 +358,7 @@ async fn test_extension_store(cx: &mut TestAppContext) {
                 slash_commands: BTreeMap::default(),
                 indexed_docs_providers: BTreeMap::default(),
                 snippets: None,
+                capabilities: Vec::new(),
             }),
             dev: false,
         },

crates/extension_host/src/wasm_host/wit/since_v0_3_0.rs

@@ -592,6 +592,8 @@ impl process::Host for WasmState {
         command: process::Command,
     ) -> wasmtime::Result<Result<process::Output, String>> {
         maybe!(async {
+            self.manifest.allow_exec(&command.command, &command.args)?;
+
             let output = util::command::new_smol_command(command.command.as_str())
                 .args(&command.args)
                 .envs(command.env)