influx2otel: convert bool type metrics to 0/1 gauge

booleans are currently unsupported https://github.com/influxdata/influxdb-observability/blob/main/influx2otel/metrics.go#L233
I think modeling them as a 0 = false, 1 = true gauge is the most appropriate behaviour, in line with prometheus conventions.

Start at influx2otel/metrics.go around line 233, where boolean metrics are currently unsupported, and trace the metric conversion path. Implement the requested 0=false and 1=true gauge behavior, then verify that boolean metrics are accepted and emitted with those values using the existing influx2otel test workflow.

Written by the indexing model from the issue text.