[Perf][C++] Bulk-copy contiguous BOUNDARY pages in the aligned reader #1075

Problem

A time range that covers only part of a chunk (e.g. a 1-day or 1-week query on a
single-chunk-per-month file) marks every page BOUNDARY, so
AlignedChunkReader::get_next_page_multi_impl falls into the row-by-row scatter
loop: one RowAppender::append per value plus a per-timestamp filter re-check.
Measured at 8.6% of a 1-week wide-table query, and it made queries reading less
data as slow as a full-month query.

Proposed changes

A BOUNDARY page under a contiguous time filter (TimeBetween with
not_between=false) has a fully matching [row_begin, row_end] range with no
interior holes, and the page is decoded whole, so its values are row-indexed at
row_begin and can take the same bulk memcpy path as FULL_PASS.

• Add Filter::is_contiguous_time_filter() (default false; TimeBetween returns
  !not_).
• Let can_bulk accept such BOUNDARY pages when no value column has nulls.
• Discrete filters (TimeIn, NOT BETWEEN) keep the slow path.

Implemented in #1072; 1-week wide-table query 1.63s -> ~1.05s.

Related: #1072