Sponsors generated from yaml

[tabathad]

This PR introduces the capability to add sponsors to the sponsor page via a YAML file, automatically sorting and styling them by tier.

To add a sponsor:

1. Create a branch: git branch -b 'sponsor-name'.
2. Append the sponsor's details to _data/sponsors.yaml:

   sponsors:
     - name: Sponsor Name
       logo: sponsor-logo.png
       url: https://sponsorwebsite.com
       description: Sponsor Name is a proud BSides Orlando Sponsor       
       level: Diamond

3. Add the sponsor's logo to assets/images/sponsors/.
4. Create a PR from your fork against site/main.
5. Upon review, merge into main.