sysutils/gcp-ops-agent: [New port] Gather logs from GCE instances

The Ops Agent is the primary agent for collecting telemetry from your
Compute Engine instances. Combining logging and metrics into a single
agent, the Ops Agent uses Fluent Bit for logs, which supports
high-throughput logging, and the OpenTelemetry Collector for metrics.
You can configure the Ops Agent to support parsing of log files from
third-party applications.

WWW: https://cloud.google.com/stackdriver/docs/solutions/agents/ops-agent

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D35107