[MLIR][Printing] ASMPrinter prints escape characters in Resources

In https://reviews.llvm.org/D157928 ellison of printing resources was added.
In the refactor, the proper printing of escape characters was mistakenly removed.
This patch adds it back in and adds a small unit test.

Reviewed By: Mogball

Differential Revision: https://reviews.llvm.org/D158700