Add log severity number to logging exporter (#6101)
Add log severity number to logging exporter (#6101)

* Add log severity number to logging exporter

Add severity number in logging exporter for logs. Requested in #6057.
Both numeric and text presentations added.
If unspecified it will show: `SeverityNumber: 0 SEVERITY_NUMBER_UNSPECIFIED`

* Update exporter/loggingexporter/internal/otlptext/logs.go

Co-authored-by: Bogdan Drutu <1078cf414b2625a240b16392085d66580bb66f4d@splunk.com>
open-telemetry/opentelemetry-collector,open-telemetry/opentelemetry-collector,open-telemetry/opentelemetry-collector