[Download] Write script to fetch and extract geometric data

[zerefwayne]

• [x] Add ArchGDAL Package
• [x] Dataset URL generator function
• [x] Download function which calls Dataset URL
• [x] Write a DataDep Register function to register dataset

[zerefwayne]

[zerefwayne]

In the latest commit, I have updated the dataset code format from GADM/Code to GADM_Code for two reasons:

1. DataDeps registers the dataset folder name via the parameter we pass it. Folder names cannot have / in their names.
2. Since we will have to replace the / with to make the folder, it will not be a consistent user experience. It's better to have while downloading and accessing it later.