feat: remove statistics collection and sql

refactor: add comments and rename 'base' to 'simple'

refactor: simple code refactoring

feat: GUC to control cc enablement and threshold

feat: count number of connected subgraphs

tests: get data for tests from 'src/test/regress/data'

feat: downgrade extension version to 0.1

feat: compatibility with pg down to 12 version including

tests: add missing data files for tests

tests: squash all test files into single file

refactor: add comments and simplify code

Initial commit