Upgradeable machines. (#2675)

* Start work on upgradeable machines.

* Upgradeable machines work

* Component requirements for upgradeable machines

* Better container handling

* Remember to not push submodule updates in your PRs, kids!

* Refresh parts after building a machine.

* NetSync false

* Address some reviews, fix some bugs

* Nullable stackhelpers dependencies

* Use container helper method to delete all entities in containers

* Nullable string in AddContainer

* Better examine for machine frame and construction in general

* Machine breakage

* Nullable node

* nullable GraphPrototype

* Re-save saltern for autolathe parts

* Fix SaveLoadSave

Content.Server/Construction/MachinePart.cs

@@ -0,0 +1,20 @@
+namespace Content.Server.Construction
+{
+    public enum MachinePart : byte
+    {
+        Capacitor,
+        ScanningModule,
+        Manipulator,
+        Laser,
+        MatterBin,
+
+        // Subspace parts.
+        Ansible,
+        Filter,
+        Amplifier,
+        Treatment,
+        Analyzer,
+        Crystal,
+        Transmitter,
+    }
+}