Implement fs module (#3)

* Implements the fs module

* Add stats object

* Add not implemented to createWriteStream

* Update mkdtemp to use tmp dir

* Unexport Stats

* Add client web socket for commands and restructure

packages/protocol/src/proto/command.proto

@@ -0,0 +1,78 @@
+syntax = "proto3";
+
+// Executes a command.
+// Ensure the id field is unique for each new session. If a client reuses the id of an existing
+// session, the connection will be closed.
+// If env is provided, the environment variables will be set.
+// If tty_dimensions is included, we will spawn a tty for the command using the given dimensions.
+message NewSessionMessage {
+	uint64 id = 1;
+	string command = 2;
+	repeated string args = 3;
+	map<string, string> env = 4;
+	string cwd = 5;
+	TTYDimensions tty_dimensions = 6;
+	bool is_fork = 7;
+}
+
+// Sent when starting a session failed.
+message NewSessionFailureMessage {
+	uint64 id = 1;
+	enum Reason {
+		Prohibited = 0;
+		ResourceShortage = 1;
+	}
+	Reason reason = 2;
+	string message = 3;
+}
+
+// Sent when a session has completed
+message SessionDoneMessage {
+	uint64 id = 1;
+	int64 exit_status = 2;
+}
+
+// Identifies a session with a PID.
+message IdentifySessionMessage {
+	uint64 id = 1;
+	uint64 pid = 2;
+}
+
+// Writes data to a session.
+message WriteToSessionMessage {
+	uint64 id = 1;
+	bytes data = 2;
+}
+
+// Resizes the TTY of the session identified by the id.
+// The connection will be closed if a TTY was not requested when the session was created.
+message ResizeSessionTTYMessage {
+	uint64 id = 1;
+	TTYDimensions tty_dimensions = 2;
+}
+
+// CloseSessionInputMessage closes the stdin of the session by the ID.
+message CloseSessionInputMessage {
+	uint64 id = 1;
+}
+
+message ShutdownSessionMessage {
+	uint64 id = 1;
+	string signal = 2;
+}
+
+// SessionOutputMessage carries data read from the stdout or stderr of the session identified by the id.
+message SessionOutputMessage {
+	uint64 id = 1;
+	enum FD {
+		Stdout = 0;
+		Stderr = 1;
+	}
+	FD fd = 2;
+	bytes data = 3;
+}
+
+message TTYDimensions {
+	uint32 height = 1;
+	uint32 width = 2;
+}