[LLDB] [Windows] Remove a TODO which probably won't be implemented

Contrary to WoW64 on x86_64, there's no struct similar to WOW64_CONTEXT
defined, for storing and handling the CPU state of an ARM32 process
from an ARM64 process. Thus, making an ARM64 lldb-server able to
control ARM32 processes seems infeasible at the moment.

(The normal CONTEXT struct has a different layout on each architecture.
In addition to this, a WOW64_CONTEXT struct always is defined, that
can store the CPU state of an x86_32 process, to allow handling it from
an x86_64 process. But there's no similar universally available struct
for ARM32.)