Fixes: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1139604
> Keeping Third-Party IP in a source control system separate from
> Microsoft source code and other assets is the preferred engineering
> practice…
Begin following this preferred engineering practice: move source code
which was copied into this repo into a separate `src-ThirdParty`
directory, so that it is easier to track and manage them.
Move the NUnitLite sources into `src-ThirdParty\NUnitLite`.
Move the force-net/crc32.net sources into
`src-ThirdParty\crc32.net`.
Move the bazelbuild/bazel sources into
`src-ThirdParty\bazel`.
Move the *C# ported* android/platform/tools/base sources into
`src-ThirdParty\android-platform-tools-base`.
Jonathan Pryor