Improve the DNSSEC keys refresh API

[rawlinp]

The current /api/1.4/cdns/dnsseckeys/refresh endpoint should be modified/enhanced:

• Return a 202 Accepted to indicate that the request was received successfully but further processing is occurring in the background.
• The 202 response should also include a link to a separate API endpoint that shows the current status of the refresh job that was kicked off (this means also implementing that separate API endpoint)
• The refresh endpoint should also be changed to a PUT because mutation should not be done in a GET.

[mitchell852]

Added the major label because GETs that write are dangerous imo.

[rob05c]

The refresh endpoint should also be changed to a POST because mutation should not be done in a GET.

Added the major label because GETs that write are dangerous imo.

It's not just extremely dangerous and deceptive, it's a violation of the HTTP spec.