feat: Add ConnectionString method to API

[deinok]

Hi,

In my case, I need to generate a InfluxDBClientOptions from a connection string.
That InfluxDBClientOptions is added to a DI as a singleton and after that an InfluxDBClient is generated as a scope.

Thats why i need that method to be with public visibility

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• dotnet test completes successfully
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #260 (b8eda67) into master (ff3ce7d) will not change coverage.
The diff coverage is n/a.

❗ Current head b8eda67 differs from pull request most recent head a0bb613. Consider uploading reports for the commit a0bb613 to get more accurate results

@@           Coverage Diff           @@
##           master     #260   +/-   ##
=======================================
  Coverage   84.84%   84.84%           
=======================================
  Files          73       73           
  Lines        6473     6473           
=======================================
  Hits         5492     5492           
  Misses        981      981           

Impacted Files	Coverage Δ
Client/InfluxDBClientOptions.cs	95.28% <ø> (ø)

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[bednar]

@deinok thanks for your PR 👍

Can you please satisfy PR Checklist before merge into master?

Thx

[deinok]

Hi @bednar everything signed and modified the CHANGELOG.md

[bednar]

LGTM