Propagate off-the-recordness to URL request context.
Propagate off-the-recordness to URL request context.

This is necessary because we use `persist:tor' since for hysterical
raisins there's only one normal `private' partition with in_memory_ =
true.  We use the virtual method IsOffTheRecord() to discriminate
instead.

Fixes https://github.com/brave/muon/issues/608.
Fixes https://github.com/brave/browser-laptop/issues/14392.

Auditors: da39a3ee5e6b4b0d3255bfef95601890afd80709@darkdh

brave/muon,brave/muon,brave/muon,brave/electron,brave/electron,brave/electron,brave/electron,brave/muon,brave/muon,brave/electron,brave/electron,brave/muon