Forcing post-build to get triggered when building

[adriengivry]

Previously, the solution was suffering from the issue I've already talked about there:

https://stackoverflow.com/questions/60539041/visual-studio-c-multiple-project-solution-setup (See 2.6.2 Post-Build limitation)

Let's consider a simple dependency case:
C is dependent of B and B is dependent of A.
C is an executable, and B and A are libraries
B and A post-build events update their Build$(ProjectName)\ directory
When changing the source code of A, then compiling it, Build\A\ will get updated. However, as B has been previously compiled (Before A changes), its Build\B\ folder contains a copy of previous A binaries and includes. Thus, executing C (Which is only aware of B as a dependency), will use old A binaries/includes. A workaround I found for this problem is to manually trigger B post-build event before executing C. However, forgetting to trigger an intermediate project post-build can result into headaches during debugging (Not loaded symbols, wrong behaviour...).

This PR fixes this issue by forcing triggering post-build events of every projects of the solution when building.
This means that we can now modify a file in OvRendering and directly hit play, the new OvRendering.dll will correctly be propagated to the OvEditor.