Support URL versioning

[AquilaSands]

When an API includes versioning in the URL this prevents httprepl listing endpoints.

With an OpenAPI description of

{
  "openapi": "3.0.1",
  "info": {
    "title": "Some API",
    "description": "A url versioned API.",
    "version": "v1"
  },
  "paths": {
    "/api/v{version}/weatherforecast": {
      "get": {
        "tags": [
          "WeatherForecast"
        ],
        "summary": "Gets a list of weather forecasts.",
        "operationId": "GetForecasts",
        "parameters": [
          {
            "name": "version",
            "in": "path",
            "required": true,
            "schema": {
              "type": "string"
            }
          }
        ], 
...

When connected to httprepl this results in the following output

https://localhost:5001/api> ls
.            []
..           []
v{version}   []

https://localhost:5001/api> cd v1
Warning: The '/api/v1' endpoint is not present in the OpenAPI description
/api/v1    []

https://localhost:5001/api/v1> ls
.    []
..   []

This only affects the discoverability as the calls can still be made and it is possible to work around the issue by navigating to the placeholder to discover endpoints e.g.

https://localhost:5001/api> cd v{version}
/api/v{version}    []

https://localhost:5001/api/v{version}> ls
.                 []
..                []
weatherforecast   [GET|POST]