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

luau_lsp_settings.json

@@ -4,6 +4,7 @@
   },
   "luau-lsp.require.mode": "relativeToFile",
   "luau-lsp.require.fileAliases": {
-    "@jecs": "lib/jecs"
-  }
+    "@jecs": "Packages/jecs"
+  },
+  "luau-lsp.platform.type": "roblox"
 }