profiler: add support for dynamic tags

[awwalker]

For #433

The issue mentions adding tests but I was a little unsure about the best way to add tests to the profiler because of the upstream instantiation. I added a couple of unit tests to the session which the profiler wraps instead but happy to revisit tests if y'all have some guidance on the best way to test the profiler

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #437 (1fea430) into main (bac1171) will increase coverage by 0.03%.
The diff coverage is 20.84%.

@@            Coverage Diff             @@
##             main     #437      +/-   ##
==========================================
+ Coverage   51.51%   51.53%   +0.03%     
==========================================
  Files         125      125              
  Lines        5683     5719      +36     
==========================================
+ Hits         2927     2947      +20     
- Misses       2472     2487      +15     
- Partials      284      285       +1     

Impacted Files	Coverage Δ
pkg/agent/profiler/profiler.go	0.00% <0.00%> (ø)
pkg/agent/session.go	63.91% <62.50%> (+5.27%)	⬆️
pkg/agent/upstream/remote/remote.go	57.36% <0.00%> (-5.88%)	⬇️
pkg/exec/cli_unix.go	9.44% <0.00%> (-1.88%)	⬇️
pkg/exec/cli.go	46.48% <0.00%> (-0.70%)	⬇️
pkg/server/render.go	67.47% <0.00%> (+2.77%)	⬆️

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[petethepig]

Looks good, thank you @awwalker !