RNW shouldn't have types in the Mso namespace

[asklar]

We have a number of types in Office's namespace (e.g. redbox and its helpers), which shouldn't be there. This tracks cleaning this up.

[chrisglein]

@asklar Can you dump a list of types that are in Mso so we have a burn down list? We also have ReactUWP namespace stuff, and stuff in the facebook namespace that isn't facebook. We have some clean up to do here. May be worth writing up the rules/recommendations on namespaces. But in the near term let's identify the Mso ones and get those cleaned up.

[asklar]

Here are the types in the Mso::React namespace

ErrorFrameInfo
ErrorInfo
IReactContext
IReactHost
IReactInstance
IReactViewHost
IReactViewInstance
IRedBoxHandler
NativeModuleProvider2
ReactErrorProviderGuid
ReactHost
ReactOptions
ReactViewOptions
RekaNativeModule
ViewManagerProvider2
AsyncActionQueue
MakeReactInstance(...)
JSBundleInfo
IJSBundle
JSBundleRegistration
MakeRegisteredJSBundle(...)
GetRegisteredJSBundles(...) (and similar in JSBundle.h)
JSFileBundleRegistration
ReactError
ReactContext
ReactInstanceWin
ILegacyReactInstance
CreateRedBoxHandler(...)
RedBoxErrorFrameInfo
RedBoxErrorInfo
MessageDispatchQueue

[asklar]

here are the react::uwp types:

AppearanceChangeListener
AppTheme
BatchingQueueThread
DynamicAutomationProperties
FrameworkElementViewManager
FrameworkElementViewManager;
implementation::DynamicAutomationProperties
implementation::ViewPanel
IReactInstance                                                  <------ different from Mso::React::IReactInstance
IXamlReactControl
JSIEngine::Chakra
LinkingManagerModule
NativeViewManager
ReactRootControl
ResizeMode
ShadowNodeBase
TriBit
UwpReactInstanceProxy
ViewManagerProvider
ViewPanel
XamlLoadState
XamlView