Add classes representing CodeCoverage ClickHouse tables

What does this MR do and why?

Adds 3 classes needed to parse different files:

1. CodeCoverage::ClickHouse::CategoryOwnersTable: represents a category_owners table in ClickHouse, and offers functionality to create it and push data to it
2. CodeCoverage::ClickHouse::CoverageMetricsTable: represents a coverage_metrics table in ClickHouse, and offers functionality to create it and push data to it
3. CodeCoverage::ClickHouse::Table: base class for the above 2 classes

The classes are needed in the context of this work: !355.

Related to: https://gitlab.com/gitlab-org/quality/feature-readiness/team/-/issues/7

How to set up and validate locally

Although not strictly dependent on anything else, to check the correct functioning of these classes many branches need to be fetched locally:

1. Fetch these branches in this exact order, stacking each branch on top of each other so that the last branch contains the complete logic:

   1. !367 (merged)
   2. this branch
   3. !355

2. Run these commands to fetch a bunch of files locally, and store them in <project-root>/working_dir/:

   curl -o gitlab.lcov https://gitlab.com/gitlab-org/gitlab/-/jobs/11380416469/artifacts/raw/coverage/lcov/gitlab.lcov
   
   curl -o rspec-11380416038.json https://gitlab.com/gitlab-org/gitlab/-/jobs/11380416038/artifacts/raw/rspec/rspec-11380416038.json
   
   curl -o rspec-11380416056.json https://gitlab.com/gitlab-org/gitlab/-/jobs/11380416056/artifacts/raw/rspec/rspec-11380416056.json
   
   curl https://gitlab-org.gitlab.io/gitlab/crystalball/packed-mapping.json.gz | gzip -d > mapping.json

3. Run

   ruby exe/test-coverage \
     --working_dir '/local/path/to/gitlab_quality-test_tooling/working_dir/' \
     --rspec-reports-jobs 'rspec_artifact_collector_unit,rspec_artifact-collector_unit_single-redis,rspec:artifact-collector_ee_unit_single-redis,rspec_artifact-collector_ee_unit' \
     --rspec-reports-glob 'rspec/rspec-*.json' \
     --coverage-report-path '/local/path/to/gitlab_quality-test_tooling/working_dir/rspec_coverage/coverage/lcov/gitlab.lcov' \
     --test-map-url 'https://gitlab-org.gitlab.io/gitlab/crystalball/packed-mapping.json.gz'

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.