CI: Fix Mkdocs Automation

[MustafaJafar]

Changelog Description

Add a CI action to trigger MK Docs deployment on creating new tags.

Additional Notes

This PR ports ynput/ayon-core#1441 fixes for fusion addon.

Since the workflow doesn't exist in main branch yet, I had to add on push temporarily in 86ddf09 to run the action and revert it in a23a7ac.

This PR add some cosmetics:

1. Update light and dark mode icons.
2. Move requirements file to root location of the repo to avoid moving it along with the docs build.
3. Removed pyproject.toml from Automated mkdocs setup #40

Testing notes:

When testing the CI action manually (trigger from Action tab manually on GH), it will generate a dummy-build version that will be deleted as soon as a tag is created.

1. go to https://docs.ayon.dev/ayon-fusion/latest/ you should find light/dark icons are updated and the latest is pointing to test-build.

Resolves #50 .