Allow configuring exceptions raise_error should capture to display webmock errors correctly

[grosser]

I'm doing: expect { call }.to raise_error(/ABORTED/)

this triggers a http request and then it ends up as:

       expected /ABORTED/, got #<WebMock::NetConnectNotAllowedError: Real HTTP connections are disabled. Unregistered request: GET h...e.sk/projects/sfn_kubernetes/stages")

but what I want to see is:

     WebMock::NetConnectNotAllowedError:
       Real HTTP connections are disabled. Unregistered request: GET https://samson.zende.sk/locks with body '{"per_page":100,"page":1}' with headers {'Accept'=>'application/json', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'Authorization'=>'Bearer a', 'Content-Type'=>'application/json', 'User-Agent'=>'Ruby'}

       You can stub this request with the following snippet:
blah blah

... this does not surface though since raise_error captures Exception and not StandardError like minitest does. I assume changing the default would be too disruptive, so I'd suggest we make that configureable ?

workaround I'm using atm:

  undef :raise_error
  undef :raise_exception
  def expect_error(regex)
    yield
  rescue StandardError => e
    raise unless e.message.match?(regex)
  else
    raise "Nothing raised"
  end