chore: Make jecs a dependency, bump jecs to v0.3.0

+ Make jecs a wally dependency instead of a file in lib. This wasn't done earlier due to wally packages not being able to be used outside of Roblox without dynamically requiring them. Now, a script is used to download the latest source of jecsfrom Github associated with the version in the manifest.

+ Bump jecs-utils to v0.1.3 and release

.github/workflows/ci.yml

@@ -64,6 +64,15 @@ jobs:
       - name: Install Luau
         uses: encodedvenom/install-luau@v2.1
 
+      - name: Install Rokit
+        uses: CompeyDev/setup-rokit@v0.1.2
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Download Jecs
+        run: |
+          lune run download-jecs
+
       - name: Run Unit Tests
         run: |
           output=$(luau test/tests.luau)