Added: Support for BLSE (Bannerlord Software Extender)

[Sewer56]

This PR adds the following:

• Ability to install BLSE
• Ability to start game via BLSE
• Diagnostic for informing the user if BLSE is missing if the 'magic' BLSE.LoadingInterceptor or BLSE.AssemblyResolver dependencies are required.
• Diagnostic to install Harmony (required by BLSE) if missing.

Starting BLSE On Linux

Starting BLSE on Linux will start it with the more obscure /forcenetcore argument of BLSE.

Reasons are multiple:

• Steam wouldn't install .NET Framework into the WINEPREFIX by default.
• The .NET Framework installer fails on Proton (for some reason), unlike Wine.
• wine-mono (default Framework implementation) unfortunately doesn't work well with BLSE (and I believe Harmony) out the box.

Good chances are the vanilla Bannerlord launcher may already be doing it out of the box, but I haven't yet checked/confirmed it by decompilation.

Draft Notice

This is a draft because I'm waiting for upstream PR merge/release, this will need a NuGet version bump on the Bannerlord stuff once it's available. I've PR'd new APIs.