refactor(editor): unify directories naming (#11516)

**Directory Structure Changes**

- Renamed multiple block-related directories by removing the "block-" prefix:
  - `block-attachment` → `attachment`
  - `block-bookmark` → `bookmark`
  - `block-callout` → `callout`
  - `block-code` → `code`
  - `block-data-view` → `data-view`
  - `block-database` → `database`
  - `block-divider` → `divider`
  - `block-edgeless-text` → `edgeless-text`
  - `block-embed` → `embed`

blocksuite/affine/widgets/slash-menu/README.md

@@ -0,0 +1 @@
+# widget-slash-menu