expose both trace_id_high and trace_id_low in the jaeger interface

[waynexia]

minitrace-rust/minitrace-jaeger/src/lib.rs

Lines 75 to 76 in 8af58da

	trace_id_low: trace_id as i64,
	trace_id_high: 0,

Both open-telemetry's protocol and jaeger's protocol can accept up to u128 as trace id. It would be good if minitrace-jaeger also provided the similar API

[waynexia]

I'm willing to make this change if it sounds reasonable 🤗

[andylokandy]

TraceId is changed to u128 in #153