The first step towards enabling Facbook's flow in the project. The flow
configuration is pristine as generated by react-native upgrade.

In preparation for and as another early step in rewriting the Web
version of jitsi-meet using React, use Haste resolver which is able to
distinguish among platform-independent files, Web-specific and
mobile-specific ones.

Additionally, (1) make sure that Babel is capable of understanding React
files and (2) introduce React as a dependency.

The purpose is to repeatedly take small steps towards our goal and merge
them before they get in conflict with the separate ongoing advancement
of the Web version of jitsi-meet.

React Native's module bundler (aka packager) has its default Babel
preset - react-native/babel-preset - which it uses in the absence of a
custom .babelrc. Unfortunately, the default may be tripped by the
presence of a .babelrc in dependencies. Additionally, if the default
does not get tripped, the npm install of lib-jitsi-meet as a dependency
may fall into a recursion in which Babel attempts to transpile
react-native/babel-preset. To reduce the risks of stumbling upon such
problems, move Babel's configuration inside the Webpack configuration
file.

Enable ESLint on jitsi-meet with the same configuration and the same
goals as in lib-jitsi-meet.