message: feat(error): add `Error::is_connect` method
  This allows inspecting errors to determine if they are from a client
  trying to establish a connection (from the `Connect`).
diff: @@ -97,13 +97,6 @@ pub(crate) enum User {
  */
  impl Error {
  - //TODO(error): should there be these kinds of inspection methods?
  - //
  - // - is_io()
  - // - is_connect()
  - // - is_closed()
  - // - etc?
  -
  /// Returns true if this was an HTTP parse error.
  pub fn is_parse(&self) -> bool {
  match self.inner.kind {
  @@ -139,6 +132,11 @@ impl Error {
  self.inner.kind == Kind::Closed
  }
  + /// Returns true if this was an error from `Connect`.
  + pub fn is_connect(&self) -> bool {
  + self.inner.kind == Kind::Connect
  + }
  +
  /// Returns the error's cause.
  ///
  /// This is identical to `Error::cause` except that it provides extra
  