Migrate all mechs to PartAssembly and remove legacy MechAssemblySystem (#39027)

* Removed the old MechAssembly system and component.
Converted all mechs to use the unified PartAssembly system.
Removed dismantling mechs during assembly logic to simplify the code.

* Delete Chassis via migration

Resources/Prototypes/Recipes/Construction/Graphs/mechs/hamtr_construction.yml

@@ -6,6 +6,9 @@
     edges:
     - to: hamtr
       steps:
+      - assemblyId: Hamtr
+        guideString: mech-construction-guide-string
+
       - tool: Anchoring
         doAfter: 1
         completed:

Resources/Prototypes/Recipes/Construction/Graphs/mechs/honker_construction.yml

@@ -6,6 +6,9 @@
     edges:
     - to: honker
       steps:
+      - assemblyId: Honker
+        guideString: mech-construction-guide-string
+
       - tool: Honking
         doAfter: 1
         completed:

Resources/Prototypes/Recipes/Construction/Graphs/mechs/ripley_construction.yml

@@ -6,6 +6,9 @@
     edges:
     - to: ripley
       steps:
+      - assemblyId: Ripley
+        guideString: mech-construction-guide-string
+
       - tool: Anchoring
         doAfter: 1
         completed:

Resources/Prototypes/Recipes/Construction/Graphs/mechs/vim_construction.yml

@@ -6,6 +6,9 @@
     edges:
     - to: vim
       steps:
+      - assemblyId: Vim
+        guideString: mech-construction-guide-string
+
       - tag: VoiceTrigger
         name: construction-graph-tag-voice-trigger
         icon: