Add scalable AIP arguments

[verovaleros]

Description

closes #73

This PR introduces a key change in the argument parsing of AIP, that is, the use of argparse subparser commands.

Why? We expect to have growing functionality in AIP which may not be fully related to the normal generation of blocklists, such as metrics, running models for a given time frame, etc. We thought better to have these as commands that can be invoked.

The main changes after introducing this are:

• Migrate --rebuild-kb to subparser command rebuild-knowledge-base
• Migrate --date and --model to subparser command run-models
• Test to make sure it maintain current functionality (bin/aip still runs the default all models for date.today())

General usage

Command run-models

Command rebuild-kb

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

Run AIP with multiple scenarios: without commands, with commands, with some arguments, with dates in the past, rebuilding the knowledge base, etc.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

Changes to the documentation

• I have made corresponding changes to the documentation