Godot SDK and Blackholio tutorial

[lisandroct]

Description of Changes

Very small additions to the C# SDK specific for Godot.
I wrote the Godot Blackholio tutorial and updated the Unity one.
I added the image assets necessary for the tutorial.
I added the files for the Godot demo.

API and ABI breaking changes

No breaking changes.

Expected complexity level and risk

1. There's really no risk for current systems or projects, it's all new additions to support nicely(-ish) Godot, new Blackholio demo for Godot and updates to the tutorials.

Testing

• Follow the tutorial and verify everything works.
• Build for Windows and verify it works.
• Build for Mac and verify it works. (Will do this once I'm back home)
• Build for Linux and verify it works. (Will do this once I'm back home)
• Build for Android and verify it works. (Will do this once I'm back home)
• Build for iOS and verify it works. (I don't own any iOS devices)
• Build SDK
• Publish to Nuget

[rekhoff]

I was only able to get part-way through docs/docs/00100-intro/00300-tutorials/00500-godot-tutorial/00300-part-2.md before hitting a blocker with the implementation.
The tutorial so far it looks good with only some minor nits, but the NuGet package issue will need to get addressed before I can finish reviewing.

[rekhoff]

Update this with a screenshot of the Godot implementation, or removed it from the tutorial for now.

[rekhoff]

I think this link is broken. Also, when going to download Godot 4.6.2, for Windows, macOS, and Linux, there is a Standard and a .NET install. I don't see all call out to use the .NET (on the download page it does say ".NET builds offer support for C# as a scripting language.", but it might be good to call out the .NET version, unless either will work.

[rekhoff]

Suggested change

	2. **Rename the GameObject**:
	2. **Rename the root Node**:

[rekhoff]

I don't believe this will work to allow Godot to have code only relevant to it within the NuGet packages. Unity is able to get away with unique build flags because we have Unity developers Import the SpacetimeDB SDK using the C# SDK repo. This means for Unity developers, the original code is intact and constants like UNITY_5_3_OR_NEWER and UNITY_EDITOR are evaluated locally. Only the SpacetimeDB.BSATN.Codegen.dll and SpacetimeDB.BSATN.Runtime.dll are pre-built head of time.

When we publish the NuGet packages for the general C# developers, that will strip out the GODOT build flag because it's not included as a constant during compilation. If we did include it, that would make it available to all SDK users (which of course would break things since it's specifically imports using Godot.

We'll likely need another approch than using GODOT build flags, or would need to make a custom target framework specifically for this.

For additional context, if we follow the tutorial, but point at a local NuGet package build from the lisandro/godot-blackholio branch, we'd get the errors like:

GameManager.cs(43,23): Error CS0117 : 'AuthToken' does not contain a definition for 'TryGetToken'
GameManager.cs(49,9): Error CS0103 : The name 'STDBUpdateManager' does not exist in the current context

And again, this is because the code is getting stripped out.

[rekhoff]

See my other note about this getting stripped out from the NuGet package during compilation.

[rekhoff]

Again, see my other note about this getting stripped out from the NuGet package during compilation.

[rekhoff]

And one more: see my other note about this getting stripped out from the NuGet package during compilation.