This patch replaces the previous `-UsePython` flag with `-NoPython`.
Essentially this flag replaces the native messenger installation
behavior with the following new strategy on Windows:
* Look for Python-3 in user's Windows environment
- If Python-3 is found, install `native_main.py` as the native
messenger binary
- If Python-3 is _not_ found, install `native_main.exe` as the
native messenger binary
This commit adds support for comiling `native_main.py` into
`native_main.exe` using [PyInstaller][0].
By default, the Powershell installer script would use the compiled
EXE version for Windows. However, the old behaviour can achieved by
using the `-UsePython` flag to `win_install.ps1`.
Currently, the `native_main.exe` is built every time
`scripts/build.sh` is invoked. However, this behavior can be
adjusted by invoking the build script as shown below:
```
PYINSTALLER="0" npm run build
```
[0]: https://www.pyinstaller.org
