[analyzer] Retrieve a value from list initialization of constant array...

[analyzer] Retrieve a value from list initialization of constant array declaration in a global scope.

Summary: Fix the point that we didn't take into account array's dimension. Retrieve a value of global constant array by iterating through its initializer list.

Differential Revision: https://reviews.llvm.org/D104285

Fixes: https://bugs.llvm.org/show_bug.cgi?id=50604