This check should occur on the shard level, but because
blobstor components expose `Open(readOnly bool)` interface,
it is reasonable to expect an error here.
Signed-off-by: Evgenii Stratonikov <evgeniy@morphbits.ru>
1. Move compression parameters to the `shard` section.
2. Allow to use multiple sub-storage components in the blobstor.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
