feat: add possibility to authenticate by username/password

[bednar]

Closes #421

Proposed Changes

Added possibility to authenticate by username/password.

Checklist

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

[codecov-commenter]

Codecov Report

Merging #435 (83e017c) into master (60438b2) will increase coverage by 1.18%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #435      +/-   ##
==========================================
+ Coverage   88.16%   89.35%   +1.18%     
==========================================
  Files          38       38              
  Lines        3210     3249      +39     
==========================================
+ Hits         2830     2903      +73     
+ Misses        380      346      -34     

Impacted Files	Coverage Δ
influxdb_client/_async/api_client.py	51.42% <100.00%> (+4.98%)	⬆️
influxdb_client/_sync/api_client.py	73.21% <100.00%> (+3.92%)	⬆️
influxdb_client/client/_base.py	98.12% <100.00%> (+0.04%)	⬆️
influxdb_client/client/influxdb_client.py	98.73% <100.00%> (ø)
influxdb_client/client/influxdb_client_async.py	91.37% <100.00%> (ø)
influxdb_client/rest.py	86.20% <100.00%> (+3.59%)	⬆️
influxdb_client/configuration.py	87.91% <0.00%> (+4.39%)	⬆️
influxdb_client/_async/rest.py	78.22% <0.00%> (+12.90%)	⬆️

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