Project upgrade feature

Feature request:

To be able copy build/run settings from other projects into new version of Qt.

User story:

"Suppose that I run the maintenance tool and install a new version of Qt.
Suppose also I want to build my project for that version with all the special build targets that I had defined for the older version of Qt.

Then I would like to be able not to configure the new Qt version from the raw
toolkit options (as I get now when a project is not yet configured) but the
have the option to be able copy build/run settings to be used in other projects.

So I can say 'Yes please configure for this new Qt version but use all the
settings and compile flags and qml debug settings etc from that previous
version"