[Voyageurs] Add a basic ps/2 keyboard driver.

lib/mammoth/ipc/port_client.cpp

@@ -15,4 +15,8 @@ glcr::ErrorCode PortClient::WriteString(glcr::String str, z_cap_t cap) {
       ZPortSend(port_cap_, str.length() + 1, str.cstr(), 1, &cap));
 }
 
+glcr::ErrorCode PortClient::WriteByte(uint8_t byte) {
+  return static_cast<glcr::ErrorCode>(
+      ZPortSend(port_cap_, 1, &byte, 0, nullptr));
+}
 }  // namespace mmth

lib/mammoth/ipc/port_client.h

@@ -17,6 +17,8 @@ class PortClient {
 
   glcr::ErrorCode WriteString(glcr::String str, z_cap_t cap);
 
+  glcr::ErrorCode WriteByte(uint8_t byte);
+
   z_cap_t cap() { return port_cap_; }
 
   bool empty() { return port_cap_ == 0; }

lib/mammoth/ipc/port_server.h

@@ -9,6 +9,7 @@ namespace mmth {
 
 class PortServer {
  public:
+  PortServer() {}
   static glcr::ErrorOr<PortServer> Create();
   static PortServer AdoptCap(z_cap_t cap);