[analyzer][solver] Introduce reasoning for not equal to operator

With this patch, the solver can infer results for not equal (!=) operator
over Ranges as well. This also fixes the issue of comparison between
different types, by first converting the RangeSets to the resulting type,
which then can be used for comparisons.

Patch by Manas.

Reviewed By: steakhal

Differential Revision: https://reviews.llvm.org/D112621