Disallowed changes for "seamless" project reload

_This is a work in progress_

This is tracking the disallowed changes to a project file for "fast" project reload to kick in, changes of these properties will force a full reload:
### ProjectGuid property

While we're removing the `` by default, for compatibility and cross solution reasons, we'll still return it if its present in the project file. Does the solution handle the fact that the project GUID will change over the lifetime of a project? Probably not.
### ProjectTypeGuids property

If we don't opt flavors into CPS by default, this will mean a change from a flavored project to a non-flavored project or vice versa, will result in a completely different project system loading. We should force a full reload in this case.
### TargetFrameworkIdentifier, TargetFrameworkVersion, TargetFrameworkProfile properties

Setting these currently via the hierarchy causes the project to reload.