Add a fetch config for devtools (internal).
Add a fetch config for devtools (internal).

This change has precedent, c.f. 04d16a561 for infra_internal.

R=yangguo

Bug: None
Change-Id: I089b114bcfe110ad138284bb71802cfc5d7f157d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3782488
Reviewed-by: Yang Guo <1cf0af8245a3a17a632a2c73531392b0f9761c76@chromium.org>
Reviewed-by: Aravind Vasudevan <dbe94b625b74f03bb5e24a737a4f1e15753433de@google.com>
Commit-Queue: Thiago Perrotta <660c40383373240e945f6beab69fd6841cb4aa33@chromium.org>

CoherentLabs/depot_tools,CoherentLabs/depot_tools