A simulateScreenOrientationChange method is created in targetConfigurationCommand
since we need to reach both the parent process (to call setRDMPaneOrientation),
and the content process in some cases (to dispatch an orientationchange event).

Another change was needed to ensure the orientation was set early enough in the
document lifecycle: when a new browsing context is created, we want to call
setRDMPanOrientation again, to "persist" the orientation. But the method bails
if browsingContext.inRDMPane isn't true, which is not the case when we get
the new browsing context.
In such case, we check if inRDMPane was true in the previous browsing context,
and we set it again on the new one, before re-applying the configuration.

Since the command needs RDM to be open to be effective, we're not adding a test
directly in the target configuration command folder, but extend an existing RDM
test to cover more cases.
Note that calling setRDMPaneOrientation on the browsing context does not apply
the orientation to iframes (See Bug 1704830), which is why we don't test it in
the test.

Depends on D111262

https://hg.mozilla.org/mozilla-central/rev/8547a3453ff2