fix(editor): behavior of deleting at the start of line (#12787)

Close BS-3182, #12736 




#### PR Dependency Tree


* **PR #12787** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Bug Fixes**
- Improved the behavior when deleting empty lines and merging blocks,
ensuring more accurate handling of block deletion and cursor focus in
various scenarios.
- **Tests**
- Added new end-to-end tests to verify correct deletion of lines in
edgeless text and paragraph blocks, including checks for block removal
and cursor position.
- Introduced a utility function to retrieve block IDs for testing
purposes.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

tests/blocksuite/e2e/utils/actions/block.ts

@@ -23,3 +23,9 @@ export async function updateBlockType(
   );
   await waitNextFrame(page, 400);
 }
+
+export async function getBlockIds(page: Page) {
+  return page.evaluate(() => {
+    return window.host.std.store.getAllModels().map(m => m.id);
+  });
+}