Use windows-2019 as build machine

[licanhua]

I'm trying to consolidate my investigation on disk usage in this thread.
It's better to complete #3476 before this task. it will save 4G on D and reduce the build time of 16 minutes.

Here are something interesting:

1. The installation of VS v141 dependencies consumes 4.1G on D, and spend 16 minutes on pipeline. It’s better to use v142 in windows-2019 build machine
2. ReactNative in vnext requires at least 3G space to finish the compilation, after removing .pch, its final size reduced to 1.5G
3. Nuget for the solution consumes 1.7G. If we have multiple solutions to build in one job, we can consolidate all projects into one solution.

Driver D usage if build machine is vs2019
D capacity: 15G, free: 13G
After checkout: 12.7G
After yarn install: 11.8G
After install VS dependencies: 7.7G (4.1G)
After NuGet restore – Playground: 6.0G (1.7G)
After build playground: 4.1G
After Nuget restore – SampleApp: 2.3G
After build sample app: 1.3G

Some diffs between vs2017-windows2016 and windows-2019:

1. vs2017-win2016 is prior to RS1, so we can’t react-native UWP application on it, also have problem to install framework package like Microsoft.UI.Xaml
2. Both windows-2019 and vs2017-win2016 has 15G on D, but vs2017-win2016 has more than 120GB free space on C: while windows-2019 has less than 10G.
3. We can’t use C# 7.1 and above features on vs2017-win2016

Some improvement I made:
#3773 reduce build flavors for RNWUniversalPR
#3768 Redirect build directory to C: on vs2017-win2016 build machine
#3771 Delete .pch after build on pipeline
#3734 Reduce build time on pipeline
#3729 Use ReactNative.V8JSI.Windows.0.1.6 and ReactNative.Hermes.Windows.0.1.6