Co-authored-by: James Bunch <fallwith@gmail.com>

Previously, trace_id, span_id, and trace_flags were assigned based on
the OpenTelemetry::Trace.current_span's SpanContext. The specification
requires a context be accepted as an argument on emit.

If no context is provided, OpenTelemetry::Context.current will be used.

If there isn't a current span on OpenTelemetry::Context.current
trace_id, span_id, and trace_flags will be nil unless they are passed
as arguments.

Also, remaining #emit methods are renamed to #on_emit.

This code was leftover and should have been removed.
Now, the specfic `trace_id`, `span_id`, and `trace_flags`
attributes are used instead.

…lemetry-ruby into logs-sdk-log-record

Convert Time to the appropriate nanosecond format in LogRecordData.
Remove Float option from argument declaration.

The LogRecordData definition says the time is already
Integer nanoseconds since epoch, so move the logic to convert
the timestamp to LogRecord#to_log_record_data

* Follow the pattern in TracerProvider#internal_start_span
* Update spacing in LogRecordData
* Remove resource references outside LoggerProvider
* Remove Logger attr_readers for logger_provider and
  instrumentation_scope