Allow adjusting Docker parameters for any Postgres container. Use --set-shm=1g for all Postgres containers by default

When restoring from a backup, we're running a Postgres container without using --set-shm=1g – so in some cases, it fails with this error:

ERROR : cloud not resize shared memory segment "/PostgreSQL.XXXXXXXX" to YYYYYYYY bytes: no space left on device

This is what we already bumped into clones' containers #225 (closed) and solution two steps:

• support containerConfig in DLE configuration (however, only for clones)
• use "shm-size": 1gb by default in all config examples (e.g., https://gitlab.com/postgres-ai/database-lab/-/blob/6cce8d6c673ae0f8dbf736b2b94ab0ea8d75d474/configs/config.example.logical_generic.yml#L103)

TODO:

• allow containerConfig for all Postgres containers
• use "shm-size": 1gb by default for all of them too.

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On a separate note, this issue raises the question of global configuration for all Postgres containers again -- it would be good at some point to implement a "global" section where we can set properties for all Postgres containers, starting from image that is to be used, Postgres version, extensions loaded, PG config parameters, Docker parameters. "Local" configuration would be still supported, overriding some particular parts, what would be quite rare (an obvious example here is the need to override shared_buffers for "sync" containers in "physical" mode to replay WALs faster – but we would have only a few such items).