MockWebServer: Create Vert.x implementation bridge classes

[manusa]

Description

Part of #5719

To be able to replace the MockWebServer implementation based on OkHttp to Vert.x, we need to provide a set of Vert.x based classes provide or bridge the required OkHttp functionality.

These classes should be added to the io.fabric8.mockwebserver.vertx package.

The following list contains the classes to implement:

• Protocol: equivalent to okhttp.Protocol enum containing the available HTTP protocols.
  Contains mapping to the io.vertx.core.http.HttpVersion
• HttpServerRequestHandler: Vert.x HTTP Handler implementation.
  Handles the HTTP requests received by the MockWebServer.
  Computes a MockResponse and builds the appropriate Vert.x response.
  In case the MockResponse is a WebSocket, it takes care of upgrading the connection.
• ServerWebSocketHandler: takes care of the upgraded HTTP connections that are converted to WebSocket.
  Bridges the calls to/from the Vert.x WebSocket from/to the MockWebServer WebSocketListener from the server side.
• VertxMockWebSocket: MockWebServer WebSocket implementation.
  Bridges the calls to/from the Vert.x WebSocket from/to the MockWebServer WebSocketListener from the client side.