Refactor ExecServer filesystem split between local and remote (#15232)

For each feature we have:
1. Trait exposed on environment
2. **Local Implementation** of the trait
3. Remote implementation that uses the client to proxy via network
4. Handler implementation that handles PRC requests and calls into
**Local Implementation**

codex-rs/exec-server/src/file_system.rs

@@ -0,0 +1,65 @@
+use async_trait::async_trait;
+use codex_utils_absolute_path::AbsolutePathBuf;
+use tokio::io;
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct CreateDirectoryOptions {
+    pub recursive: bool,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct RemoveOptions {
+    pub recursive: bool,
+    pub force: bool,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct CopyOptions {
+    pub recursive: bool,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct FileMetadata {
+    pub is_directory: bool,
+    pub is_file: bool,
+    pub created_at_ms: i64,
+    pub modified_at_ms: i64,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct ReadDirectoryEntry {
+    pub file_name: String,
+    pub is_directory: bool,
+    pub is_file: bool,
+}
+
+pub type FileSystemResult<T> = io::Result<T>;
+
+#[async_trait]
+pub trait ExecutorFileSystem: Send + Sync {
+    async fn read_file(&self, path: &AbsolutePathBuf) -> FileSystemResult<Vec<u8>>;
+
+    async fn write_file(&self, path: &AbsolutePathBuf, contents: Vec<u8>) -> FileSystemResult<()>;
+
+    async fn create_directory(
+        &self,
+        path: &AbsolutePathBuf,
+        options: CreateDirectoryOptions,
+    ) -> FileSystemResult<()>;
+
+    async fn get_metadata(&self, path: &AbsolutePathBuf) -> FileSystemResult<FileMetadata>;
+
+    async fn read_directory(
+        &self,
+        path: &AbsolutePathBuf,
+    ) -> FileSystemResult<Vec<ReadDirectoryEntry>>;
+
+    async fn remove(&self, path: &AbsolutePathBuf, options: RemoveOptions) -> FileSystemResult<()>;
+
+    async fn copy(
+        &self,
+        source_path: &AbsolutePathBuf,
+        destination_path: &AbsolutePathBuf,
+        options: CopyOptions,
+    ) -> FileSystemResult<()>;
+}