[TIR][Bugfix] Improved massive build times caused by tir.floormod and tir.floordiv...

[TIR][Bugfix] Improved massive build times caused by tir.floormod and tir.floordiv. Fixed Topi testcase. (#5666)

* Improved uncommon case of floormod and floordiv. Removed dependence on np floor_div and fmod.

* Fixed clang-format complaints

* Streamlined floormod and floordiv lowering logic

* Improved build times by expressing int64 case of tir FloorMod and FloorDiv using let nodes

* Updated use-def analysis and llvm codegen to support duplicated letnodes.

* Corrected misuse of var_map_ in llvm codegen

* Updated backends that support LetNode

* Changed floormod and div lowering logic to avoid using FP on systems that don't support it.

* Fixed formatting

Co-authored-by: pankratz <pankratz@ualberta.ca>