Add DynamicallyAccessedMemberTypes sugar members over existing members

It's fairly typical to want to preserve all properties, or all members on a type; this currently requires OR'ing together multiple enum values from DynamicallyAccessedMemberTypes:

```c#
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties | DynamicallyAccessedMemberTypes.NonPublicProperties)]
```

As these annotations propagate around the codebase, things start to get verbose. This could be made nicer by introducing enum members which OR other members:

```c#
[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.AllProperties)]
```

This could be done for all public/non-public pairs, as well as maybe AllMembers for both properties and fields (there may be some other opportunities).

The trimming analyzer could even have a code fix to replace the verbose form with the shorter one.