Fix kibana-upload and remove cumbersome dataclasses

[rw-access]

Issues

Closes #121

Summary

dataclasses-json was silently dropping fields, and drifted from the JSON schemas. index wasn't included in the RuleResource class definition, the field was silently dropped. I removed the dataclasses-json approach, and just made RuleResource a subclass of dict instead. There is no validation in the schema, and I think that it's okay to make the client validate, since all of that code is there.

Here's the payload after the changes

[{'author': ['Rule export'], 'description': 'The contents of crontab have been modified by a non-root user.', 'tags': ['prod'], 'index': ['filebeat-*'], 'language': 'kuery', 'license': 'Elastic License', 'name': 'Cron - Crontab entry changed', 'risk_score': 15, 'rule_id': '7230e517-3f0f-4652-8c47-c2edd9b25d19', 'severity': 'low', 'type': 'query', 'query': 'event.module: cron and event.action: changed and not user.name: root', 'threat': [{'framework': 'MITRE ATT&CK', 'technique': [{'id': 'T1053', 'name': 'Scheduled Task', 'reference': 'https://attack.mitre.org/techniques/T1053/'}], 'tactic': {'id': 'TA0002', 'name': 'Execution', 'reference': 'https://attack.mitre.org/tactics/TA0002/'}}, {'framework': 'MITRE ATT&CK', 'technique': [{'id': 'T1053', 'name': 'Scheduled Task', 'reference': 'https://attack.mitre.org/techniques/T1053/'}], 'tactic': {'id': 'TA0003', 'name': 'Persistence', 'reference': 'https://attack.mitre.org/tactics/TA0003/'}}], 'version': 1, 'meta': {'original': {'id': '9bad9907-1969-4a70-bfbd-367f0dcc0203', 'creation_date': '2020/08/11', 'ecs_version': ['1.5.0'], 'maturity': 'development', 'updated_date': '2020/08/11'}}}]

[brokensound77]

Nice, LGTM if it tested fine 👍