[PERF] merge: faster intersection with zone

Steps to reproduce:
- add 1000 rows
- copy a simple value
- select a huge zone (all columns, all rows)
- paste
=> watch your browser burn. The process never ends.

closes #4225

Task: 3924969
X-original-commit: 4903083
Signed-off-by: Pierre Rousseau (pro) <[email protected]>

Author: LucasLefevre

src/plugins/core/merge.ts

@@ -187,9 +187,12 @@ export class MergePlugin extends CorePlugin<MergeState> implements MergeState {
    * if they have at least a common cell
    */
   doesIntersectMerge(sheetId: UID, zone: Zone): boolean {
-    return positions(zone).some(
-      ({ col, row }) => this.getMerge({ sheetId, col, row }) !== undefined
-    );
+    for (const merge of this.getMerges(sheetId)) {
+      if (overlap(zone, merge)) {
+        return true;
+      }
+    }
+    return false;
   }
 
   /**