[owners] Add leszeks@ as per-file factory owner

Change-Id: I2fed918353fea7c4fe42d6aef6e064e143111057
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2050392
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66224}

src/heap/OWNERS

@@ -3,4 +3,6 @@ hpayer@chromium.org
 mlippautz@chromium.org
 ulan@chromium.org
 
+per-file *factory*=leszeks@chromium.org
+
 # COMPONENT: Blink>JavaScript>GC