feat: OTel metrics & metering

[nosahama]

About this change - What it does

• we add OTel metering and HTTP metrics to the service.
• the metrics are exported to prometheus via the opentelemetry-collector as shown below

• no changes to the grafana dashboard shows that the prometheus source still works as expected

Follow up

• update the schema_reader metrics to use the OTel meter
• maybe deprecate statsd
• close the prometheus PR instrumentation: fastapi prometheus middleware #1007 as we now use the OTel metering and exporting to prometheus, thus native prometheus instrumentation is not needed

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
src/karapace
config.py
src/schema_registry
__main__.py					20
factory.py					20, 62
src/schema_registry/telemetry
container.py
meter.py
middleware.py
setup.py					35-36
Project Total

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