Opentelemetry metrics bindings for influxive-child-svc.

Example

```rust use influxive_writer::*;

// create an influxive writer let writer = InfluxiveWriter::withtokenauth( InfluxiveWriterConfig::default(), "http://127.0.0.1:8086", "my.bucket", "my.token", );

// register the meter provider opentelemetryapi::global::setmeterprovider( influxiveotel::InfluxiveMeterProvider::new( Default::default(), Arc::new(writer), ) );

// create a metric let m = opentelemetryapi::global::meter("my.meter") .f64histogram("my.metric") .init();

// make a recording m.record(&opentelemetry_api::Context::new(), 3.14, &[]); ```