Make watermark size configurable

The torture tests were looking for the anchor tag within each
button. However, that anchor could get blown away from a react
re-render. So instead, expose a way for the torture tests
to find the root node of the button.

I'm not saying that the two commits in question were wrong or worse than
what I'm offering. Anyway, I think what I'm offering brings:

* Compliance with expectations i.e. the middleware doesn't compute the
next state from the current state, the reducer does;

* Clarity and/or simplicity i.e. there's no global variable (reqIndex),
there's no need for the term "index" (a.k.a "reqIndex") in the redux
store.

* By renaming net-interceptor to network-activity feels like it's
preparing the feature to implement a NetworkActivityIndicator React
Component which will take on more of the knowledge about the specifics
of what is the network activity redux state exactly, is it maintained by
interception or some other mechanism, and abstracts it in the feature
itself allowing outsiders to merely render a React Component.

It will only be shown when there are ongoing network requests.

Works only for XHR requests, which is the only network request mobile performs
(WebRTC traffic aside). The fetch API is implemented on top of XHR, so that's
covered too.

Requests are kept in the redux store until they complete, at which point they
are removed.

The global.performance.now polyfill is removed since it's polyfilled by
react-native-callstats.

* ref(1-on-1): move remote visibility to a selector

Derive whether or not remote videos should display using a selector
to look across different states. A selector was chosen over using
memoized selectors (reselect) or subscribers as a first step
approach, avoiding additional mutations caused by a subscriber
updating the filmstrip state and avoiding additional api overhead
introduced by reselect.

* rename selector

callstats no longer depends on it and it doesn't break when we use the latest.

few tweaks to fix some exceptions in edge

fix(external_api): isAudioMuted and isVideoMuted

* ref(recording): convert recording label to react

- Create a RecordingLabel component for displaying the current
  recording state, as reflected in the redux store. This is
  needed for 1-on-1 mode to be completely in redux.
- Update the store with the recording state so RecordingLabel
  can update itself.
- Remove previous logic for updating the non-react label, which
  includes event emitting for filmstrip visibility changes,
  as RecordingLabel is hooked into redux updates.

* ref(recording): use status and type constants from lib

* make label really dumb, move logic back to Recording

ref(toolbar): replace custom debounce with lodash throttle

Create empty elements within InlineDialog content that can be
used to bridge mouse movement from the InlineDialog trigger to
the InlineDialog content. The empty elements are positioned
absolute so they can break out of the InlineDialog container
and not affect popper's position calculations.

Skips showing empty statuses. Updates poltergeist to report connected.

I see it as the first step in simplifying the route navigate of the
JavaScript app by removing BlankWelcomePage from _getRouteToRender. From
a faraway point of view, the app is at the route at which it is not in a
conference. Historically, the route was known as the Welcome page. But
mobile complicated the route by saying that actually it may not want to
see the room name input and join button.

Additionally, I renamed BlankWelcomePage to BlankPage because I don't
think of it as a WelcomePage alternative but rather as a more generic
BlankPage which may be utilized elsewhere in the future.

I plan for the next steps to:
* Merge Entryway, _interceptComponent, and _getRouteToRender in one
React Component rendered by AbstractApp so that the whole logic is in
one file;
* Get rid of RouteRegistry and routes.

Adds multidomain support to rayo filter module.