Add tracing feature

[CathalMullan]

Pretty unintrusive of a feature to add.

Before merging, I'd like to see the performance cost through Codspeed of enabling this. I imagine it would be quite high - as such, maybe mention this is only to be used for debugging, rather than general purpose usage. e.g. enable tracing, but set logging to error, see impact.

EDIT: On reflection - maybe just focus on the search logic for now.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 67.51055% with 77 lines in your changes missing coverage. Please review.

:white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/parser.rs	5.08%	34 Missing and 22 partials :warning:
src/router.rs	84.37%	13 Missing and 2 partials :warning:
src/node/search.rs	92.10%	3 Missing :warning:
src/path.rs	25.00%	3 Missing :warning:

Files with missing lines	Coverage Δ
src/node/insert.rs	95.01% <100.00%> (+0.79%)	:arrow_up:
src/node/search.rs	80.83% <92.10%> (+1.63%)	:arrow_up:
src/path.rs	85.71% <25.00%> (-14.29%)	:arrow_down:
src/router.rs	88.70% <84.37%> (+3.07%)	:arrow_up:
src/parser.rs	78.08% <5.08%> (-20.79%)	:arrow_down:

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #169 will not alter performance

_{Comparing 168-add-tracing-support-as-an-optional-feature (6f71015) with main (f05f661)}

Summary

✅ 19 untouched benchmarks