Add utility methods for metrics export table creation in clickhouse

What does this MR do and why?

• Add utility method to metrics exporter module to create clickhouse table with correct schema for test metrics export
• Refactor clickhouse client to support basic querying and make client instances isolated and not store auth and endpoint data as class variables (allows correctly creating multiple clients with different endpoints and auth)
• Add additional hash field to have a better unique identifier for a test based on it's actual location and full name
• Normalize all paths and remove leading ./ as these are just unnecessary data
• Add feature_category by default (initial idea was to keep it as custom configurable field, but because we need it in primary index, adding it by default even though it's not very generic and mostly GitLab specific but could still be used to categorize specs)

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