feat(instrumentation-express): propagate context and measure full handler spans

[raphael-theriault-swi]

Which problem is this PR solving?

Currently the Express instrumentation does not propagate context and does not properly instrument request handlers.

Short description of the changes

Context is propagated for middleware and request handler spans, while their next callback is reset to the parent context to avoid extreme nesting as suggested in #2022. Request handler spans are also no longer ended prematurely.

Router spans are kept as-is since they are broken and propagating context for them would make things even more confusing than they already are.

Example traces

Before

After

Related issues

• Fixes @opentelemetry/instrumentation-express handler does not run in correct context #2022
• Fixes @opentelemetry/instrumentation-express handler does not account for async work #2023
• Fixes Auto instrumentation of express app is not sending exception event in trace #2146
• Fixes express instrumentation - span end prematurely for non-middleware instrumentations #2442
• Fixes Can't update span name when using OpenTelemetry Express Instrumentation for Node.js #2469
• Fixes Can't get active span in Express instrumentation. #2617
• Supersedes fix(instrumentation-express): Finish spans after execution #2603

[raphael-theriault-swi]

cc @pichlermarc fixes discussed wednesday

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.79%. Comparing base (12ee8db) to head (8d6662f).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2638   +/-   ##
=======================================
  Coverage   90.78%   90.79%           
=======================================
  Files         169      169           
  Lines        8056     8062    +6     
  Branches     1643     1645    +2     
=======================================
+ Hits         7314     7320    +6     
  Misses        742      742           

Files with missing lines	Coverage Δ
...try-instrumentation-express/src/instrumentation.ts	98.61% <100.00%> (+0.02%)	⬆️

... and 1 file with indirect coverage changes