Revert "Revert "[clang-tidy] Handle unresolved expressions in ExprMutationAnalyzer""

This is the same as D50619 plus fixes for buildbot failures on windows.
The test failures on windows are caused by -fdelayed-template-parsing
and is fixed by forcing -fno-delayed-template-parsing on test cases that
requires AST for uninstantiated templates.

llvm-svn: 341891