Create optional bill of materials output

We often get support requests of the form "this works when I build my app on my machine, but fails when I build it on CI". These usually point to a difference in build environments between the machines. Technically, the versions used for all the build tools are probably in a `.binlog`, but it takes a lot of spelunking and knowledge to be able to compare two `.binlog`'s. Some information is also available in `$(IntermediateOutputPath)build.props` but it's hidden deep in the `obj` directory.

If we made this process easier, would it empower users to self-diagnose build environment differences between machines, eliminating the need for our help?

## Possible Solution

Nothing is done by default. A user can add the following MSBuild to their project to generate a BOM manifest that is written to the `$(OutputPath)`:

```xml
true
```

The file written to the project output can be whatever format but should contain the following non-exhaustive list of information:

- OS Version
- .NET version
- Workload version(s)
- Build Tools version
- Android SDK version
- JDK version
- Cmdline Tools version
- Linker version
- Aapt2 version
- ApkSigner version
- R8 version
- etc.