chore(metastore): add columnar indexpointers reader

[ivkalita]

What this PR does / why we need it:

Similar to #20053 and #19992 I add a columnar reader for index pointers sections.

Checklist

• Rebase after chore(metastore): use column reader for blooms #20053 is merged
• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
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