Update fleet output resource to new API schema format

[taylor-swanson]

• Updated fleet output to use new schema format, where each output kind now has a strongly typed data structure to hold the relevant configuration items.
• Relocated the fleet api generators to match repo style, and cleaned up the schema downloader and filtering functions.
• Expose 'ca_trusted_fingerprint' config value
• Add test case for logstash output
• Update Fleet API version to v8.10.0

Closes #428

[tobio]

@taylor-swanson what happens when this is run against an older Elasticsearch version?

It looks like we're still running the relevant acceptance tests on 8.6+ so I'm assuming there's no compatibility issues?

[tobio]

LGTM pending the BWC question.

[taylor-swanson]

@tobio

It looks like we're still running the relevant acceptance tests on 8.6+ so I'm assuming there's no compatibility issues?

That's my understanding as well. The changes to the Fleet OpenAPI schema were to better define the output types and how the output API should be used. As far as I can tell, this doesn't actually change what data we send to the Fleet API. What it did change was the code that was generated, which necessitated this change. Thankfully, we have the acceptance tests running against the different versions to validate things still work.