Add event type information for audit events using AuditEventService in `Members`

Problem to solve

Some audit events are named audit_operation. This isn't a descriptive name and makes it difficult to differentiated from other events.

Additional context is available in this epic and in the parent epic.

Proposal

Add a meaningful name for the following events and actions that can be used to differentiate them from other events:

Event	Action	Location
Create Member	Create	file
Update Member	Update	file
Delete Member	Delete	file
Approve access request	unknown	file

Naming should follow the noun_verb format and use the past tense. For example ci_variable_created.

For events created with audit_changes we can pass the event name using the event_type argument.

audit_changes(:email, as: 'email address', event_type: 'email_address_added')

Consider this MR as an example of how to do this.

Implementation plan

1. Add an meaningful event name for the events in the Members model listed in the proposal.
   • The name should follow the noun_verb format.
2. Update the associated specs.

Notes

• For instructions on how to setup your development environment.
• For any questions regarding audit events reach out to a member of the compliance group.