chore: remove ZTools addon from build and loader (#344)

- Remove ZTools install block from src/Mod/Create/CMakeLists.txt
- Remove mods/ztools submodule entry from .gitmodules
- Remove 'ztools' from legacy fallback order in addon_loader.py
- Remove ztools imports and test classes from test_kindred_pure.py
  (TestTypeMatches, TestMatchScore, TestSelectionItemProperties,
   TestColumnToIndex, TestDatumModes)
- Remove 'ztools Workbench' from issue template component lists
- Remove mods/ztools submodule from git tracking

ZTools will be archived to a reference folder in a separate step (#345).
This is part of the UI/UX rework epic (#346).

.gitea/ISSUE_TEMPLATE/documentation.yml

@@ -29,7 +29,7 @@ body:
     attributes:
       label: Location
       description: Where should this documentation live? Link to existing pages if applicable.
-      placeholder: e.g. docs/src/guide/ztools.md, or "new page under Reference"
+      placeholder: e.g. docs/src/guide/assembly.md, or "new page under Reference"
     validations:
       required: false