feat: Add callback function for handling the SSL Certificate Validation

[bednar]

Closes #321

Proposed Changes

Add possibility to custom validation of SSL certificates:

var cert = new X509Certificate2("path_to_file");

var options = new InfluxDBClientOptions.Builder()
    .Url("http://localhost:8086")
    .AuthenticateToken("my-token")
    .RemoteCertificateValidationCallback((sender, certificate, chain, errors) => 
        errors == SslPolicyErrors.None || string.Equals(cert.Thumbprint, certificate?.GetCertHashString(), StringComparison.InvariantCultureIgnoreCase))
    .Build();

using var client = InfluxDBClientFactory.Create(options);

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• dotnet test completes successfully
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #323 (3b9e043) into master (042c900) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #323      +/-   ##
==========================================
+ Coverage   88.19%   88.21%   +0.01%     
==========================================
  Files          76       76              
  Lines        6555     6565      +10     
==========================================
+ Hits         5781     5791      +10     
  Misses        774      774              

Impacted Files	Coverage Δ
Client/InfluxDBClientOptions.cs	95.40% <100.00%> (+0.14%)	⬆️
Client/Internal/ApiClient.cs	90.26% <100.00%> (+0.35%)	⬆️

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[rhajek]

LGTM