feat: pyinstaller support

[tazlin]

This PR adds preliminary support for pyinstaller. There are a couple key concerns addressed in this PR.

• ComfyUI is packaged in hordelib releases and the PATH variable is adjusted at runtime for ComfyUI code to be located and used.
  • This is because ComfyUI is not a library and is accordingly not laid out as one.
  • PyInstaller needs hooks defined for discovery to happen appropriately during a build and the appropriate files located. See the official PyInstaller docs on hooks for more information about this.
• The third-party nodes which are also packaged work in a "normal" pip install but do not work in a PyInstaller build because implicit namespacing and other python import behavior do not carry over.
  • Of note, most of the files changes in this PR simply change imports to a "fully qualified" import, which accounts for the fact that the custom node code is not in its own package (per se) but packaged and shipped within the hordelib folder itself.