DAS sampling without data column retrieving

[Nashatyrev]

PR Description

As described in #123 we need not retrieve a column from DB when sampling, we just need to make sure it exist in DB

For this a new method was added to DataColumnSidecarCustody:

SafeFuture<Boolean> hasCustodyDataColumnSidecar(DataColumnSlotAndIdentifier columnId);

It now still does a DB query for every request, but that will be heavily optimized with a DB column indexes cache in the next PR. (the similar is not viable for the getCustodyDataColumnSidecar method)

AvailabilityChecker<DataColumnSidecar> has been changed to AvailabilityChecker<UInt64>. However there is no much sense in returning column indexes. It was just made to accomodate the existing API

Fixed Issue(s)

Fix #123

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[Nashatyrev]

Agreed on post-merge review with @zilm13