Add basic migration support for ClickHouse

What does this MR do and why?

NOTE: This MR looks very large, but more than half of the changes are renames or new fixtures.

Currently, the ClickHouse tables are setup by ClickHouseTestRunner#ensure_schema, by running db/click_house/main/*.sql files against the database.

This MR adds basic support for ClickHouse migrations:

• first commit: support classes inspired by the Active Record equivalent (https://github.com/rails/rails/blob/main/activerecord/lib/active_record/migration.rb and the clickhouse-activerecord gem). I've chosen to not rely on the equivalent ActiveRecord classes since:
  • the amount of code saved is not significant.
  • we'd need to catch any ActiveRecord exceptions and raise equivalent ClickHouse exceptions, otherwise the exception class might mislead users.
  • we would be exposed to potential bugs due to subtle changes in the base ActiveRecord classes.
• second commit: Rake targets (rake gitlab:clickhouse:migrate and rake gitlab:clickhouse:rollback, including support for VERSION, VERBOSE, and SCOPE environment variables).
• third commit: moves the existing db/click_house/main/*.sql files to db/click_house/migrate/*.rb files.

Closes #428124 (closed)

Screenshots or screen recordings

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Command	Before	After
rake gitlab:clickhouse:migrate
rake gitlab:clickhouse:rollback VERSION=20230808140217

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

• Setup a development ClickHouse server, see https://docs.gitlab.com/ee/development/database/clickhouse/clickhouse_within_gitlab.html

• Test several migration commands, such as:

  • rake gitlab:clickhouse:migrate
  • rake gitlab:clickhouse:rollback

  You can also pass specific VERSION values.

  At any point, you can run SELECT * FROM schema_migrations FINAL on the ClickHouse client (clickhouse client -d gitlab_clickhouse_development) to see the internal state of the migrations.

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.