Pass `IsOffTheRecord` through to DevTools config

We have a scenario where we store in DevTools a setting to tell us if
the user has consented to fetching data or not, and it's important that
in a "normal" window, that is persisted, but in an incognito window it
is not.

To enable us to know which setting to use, we want to tell DevTools if
the user is in an OTR (Off the record) window, so that we can use a
different setting that is stored only in `window.sessionStorage` and
therefore minimally persisted.

Bug: 356612551
Change-Id: Ifae1ff0420715580852b03bbfe88c790ce4c80f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5755942
Reviewed-by: Wolfgang Beyer <wolfi@chromium.org>
Commit-Queue: Jack Franklin <jacktfranklin@chromium.org>
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1336021}