[TI_Cybersixgill] Change from API to TAXII for the integration

[P1llus]

What does this PR do?

The initial integration used to communicate with a third party python script, in collaboration with Cybersixgill we have converted this integration to rather use the TAXII server directly, this removes all third party tools requirements instead.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

The dashboards and fields are the same, but the ingest pipeline had to be rewritten to replace the functionality initially found in the python script

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[P1llus]

Awaiting feedback from Cybersixgill on a replacement for the Range header, to retrieve more items than the current default limit of 100.
Everything else is ready to be reviewed though.

[elasticmachine]

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Build stats

• Start Time: 2022-03-09T08:16:07.482+0000

• Duration: 13 min 7 sec

Test stats 🧪

Test	Results
Failed	0
Passed	8
Skipped	0
Total	8

🤖 GitHub comments

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[P1llus]

I have now tested this with 90 days worth of data working successfully, it is fully ready for review

[efd6]

Need reformatting, check is complaining.

[P1llus]

I have a demo scheduled sometime tomorrow and will proceed with merging after that