Is your feature request related to a problem? Please describe.
As a user, I would like the option to configure NIC logging to output timestamps in UNIX time (seconds, milliseconds, or nanoseconds), instead of only the default RFC3339 format.

Describe the solution you'd like
Introduce a flag or configuration option that controls the timestamp format for both JSON and text log output.

Example inputs:

• default (rfc3339 format, current behaviour)
• unix (seconds)
• unix-ms (milliseconds)
• unix-ns (nanoseconds)

Examples

JSON with UNIX (seconds):

{"time":"1755613721","level":"DEBUG","source":{"file":"controller.go","line":1019},"msg":"Syncing default/my-release-nginx-ingress-controller-7tj7f"}

Default JSON (RFC3339):

{"time":"2025-08-19T14:29:17.492029463Z","level":"DEBUG","source":{"file":"controller.go","line":1019},"msg":"Syncing default/my-release-nginx-ingress-controller-7tj7f"}

TEXT with UNIX-ms:

time=1755619167305 level=DEBUG source=controller.go:1019 msg="Syncing default/my-release-nginx-ingress-controller-c828v"

Default TEXT (RFC3339):

time=2025-08-19T14:31:26.485Z level=DEBUG source=controller.go:1019 msg="Syncing default/my-release-nginx-ingress-controller-7tj7f"