This is the first step towards moving away from sending `url` with every
call frame when emitting the `Debugger.paused` event.

Bug: chromium:1270316, chromium:1271078
Change-Id: I2f57f21e15bf908ffb53f5c7b5862d3efa329c86
Doc: https://bit.ly/devtools-debugger-callframe-url
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3344946Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78392}