Partially fixes googleapis/google-cloud-node-core#775 (the "wrong queryParameters serialization" part)

I noticed that a parameter with type string[] in the Google Calendar API was not working as expecting while using google.options({ http2: true });. Specifically I was trying to use:

google.options({ http2: true });
google
  .calendar({
    version: "v3",
    auth: new google.auth.OAuth2(...),
  })
  .events.list({
    calendarId: ...,
    privateExtendedProperty: [`foo=bar`, `baz=asdf`],
  });

I found that the privateExtendedProperty parameter was being ignored by the server.

I traced the issue to this line. Unlike the gaxios request handler (reference), the http2 handler is not calling the paramsSerializer from the parameters. This function is used to define the correct serialization method for array parameters in apirequest.ts (reference).

My fix uses the paramsSerializer passed in from the parameters exactly as is done in gaxios.