Observe SDK: limit spans sent to sink

[nilslice]

• [ ] Go SDK
• [ ] Rust SDK
• [ ] JS SDK

The default should be applied similarly to each SDK, but have a method for configuring this at the SDK level.

For example, a possible approach is:

let mut trace_ctx = adapter.start(&mut linker, &data)?;
trace_ctx.set_trace_depth(4);

// OR.. avoiding mutability and any additional method surface area:

let config = TraceConfig {
   trace_depth: 4,
   ..default::Default(),
};
let trace_ctx = adapter.start(&mut linker, &data, &config)?;

[neuronicnobody]

Goal is to reduce the depth of profiling. Solution may vary from what's defined here.