Added OpenMP 5.0 specification based semantic checks for CRITICAL construct name resolution

As reported in https://bugs.llvm.org/show_bug.cgi?id=48145, name resolution for omp critical construct was failing. This patch adds functionality to help that name resolution as well as implementation to catch name mismatches.

The following semantic restrictions are therefore handled here:

- If a name is specified on a critical directive, the same name must also be specified on the end critical directive

- If no name appears on the critical directive, no name can appear on the end critical directive

- If a name appears on either the start critical directive or the end critical directive

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D110502