Move common primitives to src/common/primitives/

Phase 1 of #5963: reorganize building blocks (buffer, parser, input,
data, and shared utilities) under common/primitives/. Runtime code
(services, public API, CoreTerminal, InputHandler) stays in place.

Update import paths across browser, headless, addons, and tests.
Add TypeScript path mappings so common/* aliases resolve primitives
first, then the common root.

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>

test/benchmark/tsconfig.json

@@ -13,7 +13,10 @@
     "target": "es2021",
     "module": "nodenext",
     "paths": {
-      "common/*": ["../../src/common/*"],
+      "common/*": [
+        "../../src/common/primitives/*",
+        "../../src/common/*"
+      ],
       "browser/*": ["../../src/browser/*"]
     }
   },