[DOP-11906] Improve Clickhouse documentation

[dolfinus]

Change Summary

• Improved Clickhouse's documentation about reading, writing and executing statements. Previously it was just crosslinks to DBReader, DBWriter and connection own methods docstrings. Now there are more Clickhouse-specific examples and recommendations
• Added new section describing type compatibility between Clickhouse and Spark, including some recommendations for reading/writing unsupported column types.
• Added new section describing which actions should be performed to connect to Clickhouse.

See https://onetl--211.org.readthedocs.build/en/211/connection/db_connection/clickhouse/index.html

If new documentation layout will be approved, we can drop generic examples from JDBC.fetch(), JDBC.execute(), JDBC.sql(), JDBC.JDBCOptions and so on, and replace them with DB-specific documentation and examples.

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a8c8403) 94.11% compared to head (4731d92) 94.12%.
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #211      +/-   ##
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+ Coverage    94.11%   94.12%   +0.01%     
===========================================
  Files          204      204              
  Lines         7836     7836              
  Branches      1399     1399              
===========================================
+ Hits          7375     7376       +1     
+ Misses         336      335       -1     
  Partials       125      125              

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