Fix functions management in DB

[EPajares]

No description provided.

[nihar1024]

init_functions.py mostly looks good to me.

There are a few changes we could consider making:

• Drop function only if it exists locally (this could help prevent the accidental deletion of functions not created from within goat-core)
• Some functions are defined in goat-routing, these are not recreated by the script
• find_unapplied_dependencies() relies on a function's actual name being consistent with the function's filename. However, this is not always the case (e.g. fix_transmeridian_h3(), get_h3_neighbors())

[nihar1024]

Relevant changes have been submitted here:

goat-community/goat-core#41
goat-community/goat-routing#7