Add imports to fix ejecting on Android with userInterfaceStyle set

[brentvatne]

If you eject an app on Android with userInterfaceStyle set to automatic then we will add some code to MainActivity that will not work because it depends on classes that haven't been imported. This adds those imports.

[codecov-io]

Codecov Report

Merging #2001 into master will increase coverage by 0.11%.
The diff coverage is 100.00%.

Flag	Coverage Δ
#babelPresetCli	100.00% <ø> (ø)
#config	60.90% <100.00%> (+0.27%)	⬆️
#expoCli	29.09% <ø> (ø)
#expoCodemod	83.81% <ø> (ø)
#jsonFile	65.49% <ø> (ø)
#metroConfig	58.83% <ø> (ø)
#packageManager	16.67% <ø> (ø)
#plist	70.64% <ø> (ø)
#pwa	34.32% <ø> (ø)
#schemer	69.88% <ø> (ø)
#uriScheme	32.05% <ø> (ø)
#webpackConfig	53.41% <ø> (ø)
#xdl	23.37% <ø> (ø)

@@            Coverage Diff             @@
##           master    #2001      +/-   ##
==========================================
+ Coverage   44.90%   45.01%   +0.11%     
==========================================
  Files         103      103              
  Lines        4283     4291       +8     
  Branches     1036     1037       +1     
==========================================
+ Hits         1923     1931       +8     
  Misses       1635     1635              
  Partials      725      725