Introduce method for getting conflicting model files
MPS-20875 "Resolve changes in non conflicting MPS models" action should show progress monitor
Merge branch '3.2/mikev/mergehint'

Conflicts:
	plugins/vcs/common/models/jetbrains/mps/vcs/platform/actions.mps
	plugins/vcs/common/models/jetbrains/mps/vcs/platform/integration.mps
	plugins/vcs/common/source_gen/jetbrains/mps/vcs/platform/actions/ResolveNonconflictingChanges_Action.java
	plugins/vcs/common/source_gen/jetbrains/mps/vcs/platform/actions/trace.info
	plugins/vcs/common/source_gen/jetbrains/mps/vcs/platform/integration/trace.info
repeat change PersistenceUtil.loadModel() to binary data