Refs 4133: add types filter to admin tasks list

[rverdile]

Summary

Adds ability to filter admin tasks by type

Testing steps

1. Either test using frontend PR or make a request like GET /admin/tasks/?type=introspect,snapshot
2. Make sure you've created/deleted some repos and templates so you have a few task types to filter.
3. These are all the task types: https://github.com/content-services/content-sources-backend/blob/main/pkg/config/tasks.go#L4-L9

Checklist

• Tested with snapshotting feature disabled and pulp server URL not configured if appropriate

[jlsherrill]

https://issues.redhat.com/browse/HMS-4133

[jlsherrill]

⚠️ This task currently requires qe-approval, but this PR does not fully resolve the task. Please contact QE to determine appropriate testing required.

[xbhouse]

tested with API and frontend PR, looks great!

[swadeley]

Works great, thank you

content-services/content-sources-frontend#285 (comment)