refactor(instr-router): use exported strings for attributes

[david-luna]

Which problem is this PR solving?

• Updates Update usage of semantic conventions to new exported strings #2025

Short description of the changes

• Update @opentelemetry/semantic-conventions to ^1.22
• Replace SemanticAttributes.HTTP_ROUTE with exported string SEMATTRS_HTTP_ROUTE
• Update README with new semantic convention package version and key

[codecov]

Codecov Report

Merging #2099 (9051fd5) into main (dfb2dff) will decrease coverage by 0.21%.
Report is 50 commits behind head on main.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2099      +/-   ##
==========================================
- Coverage   90.97%   90.77%   -0.21%     
==========================================
  Files         146      148       +2     
  Lines        7492     7675     +183     
  Branches     1502     1539      +37     
==========================================
+ Hits         6816     6967     +151     
- Misses        676      708      +32     

Files	Coverage Δ
...etry-instrumentation-router/src/instrumentation.ts	96.15% <100.00%> (ø)

... and 8 files with indirect coverage changes