Move UseSentryTracing to different namespace

[josh-degraw]

Closes #1196

[codecov-commenter]

Codecov Report

Merging #1200 (c864431) into main (934691f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1200   +/-   ##
=======================================
  Coverage   80.51%   80.51%           
=======================================
  Files         212      212           
  Lines        6902     6902           
  Branches     1579     1579           
=======================================
  Hits         5557     5557           
  Misses        822      822           
  Partials      523      523           

Impacted Files	Coverage Δ
src/Sentry.AspNetCore/SentryTracingMiddleware.cs	73.68% <ø> (ø)

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