feat: expose HTTP response headers in InfluxDBApiException

[karel-rehor]

Proposed Changes

• Add methods to InfluxDBApiException to get StatusCode and Headers from nested HttpResponseMessage more easily.
• Unit tests of these changes
• Refactor of Integration tests to leverage a base IntegrationTest class.
• Integration test of changes to InfluxDBApiException
• In Examples adds a General/Runner.cs class for unifying running examples.
• In Examples adds an example for leveraging headers: HttpErrorHandled.cs.

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• Tests pass
• Commit messages are conventional
• Sign CLA (if not already signed)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.83%. Comparing base (aab7c3a) to head (d7b0502).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #118      +/-   ##
==========================================
+ Coverage   95.81%   95.83%   +0.02%     
==========================================
  Files          12       12              
  Lines        1098     1104       +6     
  Branches      141      143       +2     
==========================================
+ Hits         1052     1058       +6     
  Misses         11       11              
  Partials       35       35              

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[alespour]

This could be written using property getters (invocations in tests need to be modified accordingly), is that right, @bednar?
In any case, Headers/GetHeaders return value should be nullable (T?)

Suggested change

	public HttpResponseHeaders GetHeaders()
	{
	return HttpResponseMessage?.Headers;
	}
	public HttpStatusCode GetStatusCode()
	{
	return HttpResponseMessage?.StatusCode ?? 0;
	}
	public HttpResponseHeaders? Headers
	{
	get
	{
	return HttpResponseMessage?.Headers;
	}
	}
	public HttpStatusCode StatusCode
	{
	get
	{
	return HttpResponseMessage?.StatusCode ?? 0;
	}
	}

[karel-rehor]

Thanks. A Sensible suggestion. Updated accordingly.

[alespour]

There is System.Net enum for status code, eg.

Suggested change

	Assert.That(iaex.GetStatusCode().GetHashCode(), Is.EqualTo(400));
	Assert.That(iaex.GetStatusCode(), Is.EqualTo(System.Net.HttpStatusCode.BadRequest));

[karel-rehor]

Updated, following suggestion.

[alespour]

LGTM