Koa plugin enhancements

[DinaYakovlev]

Which problem is this PR solving?

In addition to #176 PR and to #273 We should able to instrument the root span name. This way it would be clear from the beginning on what request the span is about, and if in the future there would be an option to remove layers (like in the express plugin) the route will be in the root span.

Short description of the changes

using koa plugin before the change:

using koa plugin after the change:

[linux-foundation-easycla]

• ✅ Dina.Yakovlev (9eb7e3e)

• ❌ The commit (751e8f5 ,93c2cfd2c34ac2c72dd04faa105a2bfcfdbffddf ,5a4dded8489144f009d9533c442df04001dc299c) is missing the User's ID, preventing the EasyCLA check. Consult GitHub Help to resolve.For further assistance with EasyCLA, please submit a support request ticket.

[codecov]

Codecov Report

Merging #326 (5a4dded) into main (234c42f) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #326   +/-   ##
=======================================
  Coverage   95.41%   95.42%           
=======================================
  Files         115      115           
  Lines        6090     6100   +10     
  Branches      590      596    +6     
=======================================
+ Hits         5811     5821   +10     
  Misses        279      279           

Impacted Files	Coverage Δ
...ode/opentelemetry-koa-instrumentation/src/types.ts	100.00% <0.00%> (ø)
.../node/opentelemetry-koa-instrumentation/src/koa.ts	98.46% <0.00%> (+0.27%)	⬆️