Dylan/refactor/unity tutorial revamp

[dylanh724]

About

• Updated the Unity tutorial, surrounding a newly-created PR for a new Unity graybox tutorial based off @bfops 's prototype
  • Initial Exclalidraw thought process
• Less focus on Unity setup, more focus on SpacetimeDB
• Overview is a short summary
• Part 1 is a quickstart: You technically don't even need part 2 + 3 unless you want to analyze the demo
• Part 2 covers server
• Part 3 covers client, with some client-server flow coverage

Made in Unity 2022.3.20 LTS

Why?

The current tutorial:

• Focuses too much on Unity, along with its setup nuances
• Focuses on Rust, although it should be C# (since targeting Unity devs)
  • Although there is my floating PR to add a C# parity, this version is significantly improved, using the new tutorial and is forked from this PR
• Is overly bloaty and jumps around too often

⚠️ Prerequisites

1. ✅This is branched from Dylan/onboarding-upgrades open PR awaiting merge
2. ⌛This replaces the old demo with the new one - an open PR awaiting merge
   • ⌛zeke-demo-project needs to be renamed to something more official-sounding
   • ⌛[Post-Merge] Repo links currently point to a WIP fork: Need to replace refs
3. ⌛Merge the clockwork-web PR to replace the Unity tutorial static images just before you merge this

New Tutorial Feats

See root [README]()

Meta Changes

The C# reference Unity section was updated (on a side note, the old Unity section here was factually incorrect -- the .unitypackage was for the demo that included the SDK; not the SDK).

[dylanh724]

Setting this to ready status, but be sure to follow prereqs