Benchmarks for sampler accessing and modifying tracestate

[cijothomas]

Adding benchmarks for samplers, specifically targetting the impact of accessing/modifying tracestate inside sampler.
Related to #3610

[reyang]

Consider something like

opentelemetry-dotnet/test/OpenTelemetry.Tests/Metrics/InMemoryExporterTests.cs

Line 33 in e6d39b8

using var meter = new Meter(Utils.GetCurrentMethodName());

?

[codecov]

Codecov Report

Merging #3613 (468bc62) into main (b54cc80) will increase coverage by 0.20%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3613      +/-   ##
==========================================
+ Coverage   87.10%   87.31%   +0.20%     
==========================================
  Files         280      280              
  Lines       10073    10073              
==========================================
+ Hits         8774     8795      +21     
+ Misses       1299     1278      -21     

Impacted Files	Coverage Δ
src/OpenTelemetry.Api/BaseProvider.cs	66.66% <0.00%> (-33.34%)	⬇️
...Listener/Internal/PrometheusExporterEventSource.cs	16.66% <0.00%> (-11.12%)	⬇️
....Prometheus.HttpListener/PrometheusHttpListener.cs	78.66% <0.00%> (-4.00%)	⬇️
...Telemetry/Internal/SelfDiagnosticsEventListener.cs	96.87% <0.00%> (-0.79%)	⬇️
...tpListener/Internal/PrometheusCollectionManager.cs	80.48% <0.00%> (+2.43%)	⬆️
...metryProtocol/Implementation/ActivityExtensions.cs	95.05% <0.00%> (+3.29%)	⬆️
...Telemetry/Metrics/PeriodicExportingMetricReader.cs	78.18% <0.00%> (+5.45%)	⬆️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	82.35% <0.00%> (+5.88%)	⬆️
src/OpenTelemetry/ProviderExtensions.cs	90.90% <0.00%> (+9.09%)	⬆️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	77.27% <0.00%> (+40.90%)	⬆️
... and 1 more