Add alert source APIs

[rocktavious]

Resolves #

Problem

We have new APIs for working with alert sources more generically but not way to do this via opslevel-go

Solution

Codegen the structs and add the necessary client functions for this

Checklist

• I have run this code, and it appears to resolve the stated issue.
• This PR does not reduce total test coverage
• This PR has no user interface changes or has already received approval from product management to change the interface.
• Does this change require a Terraform schema change?
  • If so what is the ticket or PR #
• Make a changie entry that explains the customer facing outcome of this change

[p25marti]

LGTM!