New Audit Event: Custom HTTP headers changed for streaming audit event destination

Audit need

When custom HTTP headers are added, removed, or changed for streaming audit events, this is a sensitive change that should be recorded.

Proposal

Create a new audit event when the following occurs:

• Custom HTTP header is added for streaming audit events
• Custom HTTP header is removed for streaming audit events
• Custom HTTP header is updated for streaming audit events

Note: Include the key of the key/value pair in the description of the event but omit the value. There are potentially sensitive API keys in those pairs we do not want to expose.

Ensure that new event names are created, used, and documented for this event as needed.