Add a basic fuzzing project

[MihaZupan]

(On Windows)
As simple as running .\run-fuzzer.ps1 from src/Markdig.Fuzzing.

[MihaZupan]

It's not happening as part of build, only if you run the .\run-fuzzer.ps1 script yourself.
(The libfuzzer executable & the CLI tool that is. We are referencing the SharpFuzz NuGet package as part of the build)

I find it a little spooky to be downloading and running third-party executables as part of build.

FWIW referencing any NuGet package is effectively this.

[elmigranto]

FWIW referencing any NuGet package is effectively this.

Yes, that is spooky as well :)