Stabilize ExemplarFilter

[jack-berg]

Narrower version of #7636.

Resolves #7503.

Notably:

• Leaves out exemplar reservoir (i.e. DoubleExemplarReservoir, LongExemplarReservoir). There is no internal or public API to configure reservoirs at the moment. There is no point in stabilizing this until we make it configurable.
• Omits methods on ExemplarFilter since ExemplarFilter is not a SDK extension plugin interface according to the spec

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.17%. Comparing base (6c780f1) to head (d5e2988).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7768      +/-   ##
============================================
- Coverage     90.18%   90.17%   -0.01%     
- Complexity     7200     7203       +3     
============================================
  Files           815      816       +1     
  Lines         21738    21737       -1     
  Branches       2130     2130              
============================================
- Hits          19604    19602       -2     
- Misses         1466     1467       +1     
  Partials        668      668              

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[breedx-splk]

Looks good to me, thanks for picking this back up -- I clearly didn't have the cycles to come back to this. 😮‍💨

[breedx-splk]

Thanks, yeah without this TODO it sure looks like a weird interface. 👍🏻