apiserver: Add /report endpoint for CIS reporting

[stmcginnis]

Issue number:

Related #2731

Description of changes:

This adds a new /report endpoint. GETs to this endpoint get a list of the available reports which can then be called directly. Initially this is only /report/cis that can be used to trigger a bloodhound CIS benchmark report, returning the results. The type argument controls which report to run. Right now there is only the CIS report, but this will be expanded in the future as we add other compliance or benchmark reports.

# apiclient -u /report
[{"name":"cis","description":"CIS Bottlerocket Benchmark"}]

The bloodhound options for --level and --format are supported with:

# apiclient -u "/report/cis&level=2&format=json"

Testing done:

# apiclient -u /report
[{"name":"cis","description":"CIS Bottlerocket Benchmark"}]

# apiclient -u /report/cis
Failed GET request to '/report': Status 400 when GETing /report: Report type must be specified

# apiclient -u "/report?type=cis-k8s"
Failed GET request to '/report?type=cis-k8s': Status 422 when GETing /report?type=cis-k8s: Report type 'cis-k8s' is not supported

# apiclient raw -u "/report?type=cis&level=2&format=json"

{...}

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

[bcressey]

LGTM!