Implement Syncback to support converting Roblox files to a Rojo project (#937)

This is a very large commit.
Consider checking the linked PR for more information.

rojo-test/syncback-tests/sync_rules/input-project/default.project.json

@@ -0,0 +1,16 @@
+{
+  "name": "sync_rules",
+  "tree": {
+    "$path": "src"
+  },
+  "syncRules": [
+    {
+      "use": "text",
+      "pattern": "*.text"
+    },
+    {
+      "use": "moduleScript",
+      "pattern": "*.modulescript"
+    }
+  ]
+}

rojo-test/syncback-tests/sync_rules/input-project/src/module.modulescript

@@ -0,0 +1 @@
+-- This should be a in the file 'module.modulescript'. It should be updated to have a second line.

rojo-test/syncback-tests/sync_rules/input-project/src/text.text

@@ -0,0 +1 @@
+-- This should be a in the file 'text.text'. It should be updated to have a second line.