[core] Push down bitmap indexes for data evolution merged reads

[lilei1128]

Purpose

Enable row-level bitmap file-index pushdown for data evolution merged
file groups.

Previously, bitmap indexes could only skip an entire merged group. A
non-empty bitmap could not filter individual rows because applying it to
only one field reader would break positional alignment.

This change builds a shared bitmap selection from eligible file-index
results and applies it to every aligned reader in the merged group. The
optimization is limited to normal data files with identical row-id
ranges. Blob files, vector-store files, and non-bitmap index results
continue to use the conservative fallback path.

Tests

• Added a test verifying row-level selection with a bitmap index in a
  data evolution merged group.
• Added a test verifying intersection of bitmap selections from multiple
  field files.
• Added a test verifying OR predicate semantics for bitmap selection.
• Updated the existing deletion-vector test to verify that the shared
  bitmap selection returns live matching rows while deleted matching
  groups are skipped.