[flang][beginner] Clean-up function types creation in Optimizer/Builder/Runtime files

[vzakhari]

This comes up from @jeanPerier's comment https://github.com/llvm/llvm-project/pull/83219/files#r1506118851

We'd better use fir::runtime::getModel instead of direct MLIR/FIR types creation in Numeric.cpp, Reduction.cpp, Transformational.cpp, etc.

[llvmbot]

@llvm/issue-subscribers-flang-ir

Author: Slava Zakharin (vzakhari)

This comes up from @jeanPerier's comment https://github.com//pull/83219/files#r1506118851

We'd better use fir::runtime::getModel instead of direct MLIR/FIR types creation in Numeric.cpp, Reduction.cpp, Transformational.cpp, etc.