Refactor MlflowMetricsDataSet for a better user experience

[Galileo-Galilei]

Description

Close #73

Development notes

• Create a MlflowAbstractMetricDataSet
• Create a MlflowMetricDataSet
• Create a MlflowMetricHistoryDataSet

Checklist

• Read the contributing guidelines
• Open this PR as a 'Draft Pull Request' if it is work-in-progress
• Update the documentation to reflect the code changes
• Add a description of this change and add your name to the list of supporting contributions in the CHANGELOG.md file. Please respect Keep a Changelog guidelines.
• Add tests to cover your changes

Notice

• I acknowledge and agree that, by checking this box and clicking "Submit Pull Request":

• I submit this contribution under the Apache 2.0 license and represent that I am entitled to do so on behalf of myself, my employer, or relevant third parties, as applicable.

• I certify that (a) this contribution is my original creation and / or (b) to the extent it is not my original creation, I am authorised to submit this contribution on behalf of the original creator(s) or their licensees.

• I certify that the use of this contribution as authorised by the Apache 2.0 license does not violate the intellectual property rights of anyone else.

[codecov-commenter]

Codecov Report

Merging #227 (463f9db) into master (d626c8e) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            master      #227    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           27        30     +3     
  Lines          791       908   +117     
==========================================
+ Hits           791       908   +117     

Impacted Files	Coverage Δ
kedro_mlflow/framework/hooks/pipeline_hook.py	100.00% <100.00%> (ø)
kedro_mlflow/io/metrics/__init__.py	100.00% <100.00%> (ø)
...lflow/io/metrics/mlflow_abstract_metric_dataset.py	100.00% <100.00%> (ø)
kedro_mlflow/io/metrics/mlflow_metric_dataset.py	100.00% <100.00%> (ø)
...mlflow/io/metrics/mlflow_metric_history_dataset.py	100.00% <100.00%> (ø)
kedro_mlflow/io/metrics/mlflow_metrics_dataset.py	100.00% <100.00%> (ø)

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