Add pg_dump/pg_restore to internal library

[eminano]

This PR adds the pg_dump/pg_restore functionalities to the internal postgres library. A testcontainers package is created in order to reuse the setup for integration tests.

[github-actions]

Merging this branch will decrease overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/xataio/pgstream/internal/postgres	1.36% (-0.60%)	👎
github.com/xataio/pgstream/internal/testcontainers	0.00% (ø)
github.com/xataio/pgstream/pkg/stream/integration	0.00% (ø)

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Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/xataio/pgstream/internal/postgres/pg_dump.go	0.00% (ø)	23 (+23)	0	23 (+23)
github.com/xataio/pgstream/internal/postgres/pg_restore.go	0.00% (ø)	22 (+22)	0	22 (+22)
github.com/xataio/pgstream/internal/testcontainers/test_elasticsearch_container.go	0.00% (ø)	17 (+17)	0	17 (+17)
github.com/xataio/pgstream/internal/testcontainers/test_kafka_container.go	0.00% (ø)	23 (+23)	0	23 (+23)
github.com/xataio/pgstream/internal/testcontainers/test_opensearch_container.go	0.00% (ø)	23 (+23)	0	23 (+23)
github.com/xataio/pgstream/internal/testcontainers/test_postgres_container.go	0.00% (ø)	32 (+32)	0	32 (+32)

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/xataio/pgstream/internal/postgres/pg_dump_pg_restore_integration_test.go
• github.com/xataio/pgstream/pkg/stream/integration/setup_test.go