Configure Renovate

See merge request !2

Ignore case, to cover 'message.MESSAGE', which we encounter with the
logging-operator host-tailer.

A refactor left a spurious array slicing.

Implement S3-like backends

See merge request ai3/attic/pqlog!1

Includes AWS, GCS and Minio (generic S3). Only this last one is
actually complete, the others lack Rename() implementations.

Functionality is still completely untested, except for the internal
API changes tested in the 'local' source.

Also includes an integration test that dumps cpu/allocs/heap profiles
of the ingestion stage under load.

Compression, page size, and row group size.

Generate the correct RL / DL values for our tuples, including repeated
values (lists).