[rahulram-s]

This PR is for merging NAVDAT backend and user stories for PDB, Zenodo and NAVDAT.
'rahul_user_stories' branch has all these commits merged in single branch.

[Vedant1]

for vedant

• review navdat backend and user stories
• update docs with navdat backend
• at the end, change tools/gan/ to /tools/gan_wildfire_demo/

for rahul

• add search() for zenodo, pdb, and navdat backends
• add tests for new backends' search() in CI
• add backend examples for the new search() in examples/backends/

[Vedant1]

Should we add all these user stories to the docs? @jpulidojr

[jpulidojr]

We can add a github actions routine late to automate that via each user story readme.md