feat: Implementing cross-segment read/write for WAL based on local disk

[dracoooooo]

Rationale

Improving WAL based on local disk.

This is a follow-up task for #1552.

Detailed Changes

1. Make MAX_FILE_SIZE configurable.
2. Allocate enough space when creating a segment to avoid remapping when appending to the segment.​
3. Add MultiSegmentLogIterator to enable cross-segment reading.
4. When writing, if the current segment has insufficient space, create a new segment and write to the new segment.​

Test Plan

Unit test.