This patch adds the ability for Windows on ARM to launch either x86 or
ARM Widevine plugins. It also adds the ability for Windows on x86 to
refuse ARM binaries in case, for example, a profile is transferred
between machines.

Overall this should be a non-functional change for users at the time of
landing. It does however allow us to ship the ARM Widevine plugin to
Windows ARM users to workaround a plugin crash with the x86 Widevine
plugin. This only affects Windows 10 users (Windows 11 works fine).

Differential Revision: https://phabricator.services.mozilla.com/D167634