POC - ignore SetStatus is the status is already set to Ok

[reyang]

This is a POC for the option2 of this spec discussion.

Update: this PR now depends on the specification PR to be merged and released - open-telemetry/opentelemetry-specification#1685.

Changes

• If the status is set to Ok, freeze the status and not allow future updates (including both the status code and description).

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Design discussion issue #
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #2032 (89de005) into main (c28efc3) will decrease coverage by 0.02%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##             main    #2032      +/-   ##
==========================================
- Coverage   83.90%   83.87%   -0.03%     
==========================================
  Files         192      192              
  Lines        6195     6197       +2     
==========================================
  Hits         5198     5198              
- Misses        997      999       +2     

Impacted Files	Coverage Δ
src/OpenTelemetry.Api/Trace/ActivityExtensions.cs	89.47% <50.00%> (-4.65%)	⬇️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	76.47% <0.00%> (-5.89%)	⬇️
...ZPages/Implementation/ZPagesExporterEventSource.cs	62.50% <0.00%> (+6.25%)	⬆️

[cijothomas]

LGTM. If spec approves this decision, then we need to ask .NET Runtime to implement this.