Remove terminal.html webpack entry point and notebooks terminal code

- Delete src/Terminal/ directory (JupyterLabAppFactory, index.ts/html/css, TerminalProps)
- Delete NotebookTerminalComponentAdapter (no longer needed)
- Simplify TerminalTab to always use CloudShellTerminalComponentAdapter
- Inline TerminalProps interface into NotebookTerminalComponent
- Remove src/Terminal/**/* from tsconfig.strict.json

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tsconfig.strict.json

@@ -145,7 +145,6 @@
     "src/Platform/Emulator/**/*",
     "src/SelfServe/Documentation/**/*",
     "src/Shared/Telemetry/**/*",
-    "src/Terminal/**/*",
     "src/Utils/arm/**/*"
   ]
 }