refactors and updates

• replaced source package with fsspec
• added config model
• updated postprocess to be generic function
• added vs-common as dependency
• removed config handling in favor of vs-common
• added creation functions to further separate object initialization
• redid model to support dicts rather than lists using name
• cli now handles dot notation config substitution config.value.a1 = 42 as means of config overriding
• added different output handling options
• redid config schema
• refactored stac catalog logic with pystac
• added integration test for staccatalog
• updated test folder structure
• refactored oads unit tests

closes #6 (closed) #8 (closed)