[fir] Add FIRBuilder utility functions

Extract some code from the big ptach D111337. This patch
contains some utility functions from the FIRBuidler.

List of utility functions added:
- getRegion
- getModule
- getKindMap
- getRefType
- getVarLenSeqTy
- getRealType
- createNullConstant
- createRealConstant
- createRealZeroConstant
- createGlobal
- createGlobalConstant
- createStringLitOp
- getNamedFunction
- getNamedGlobal
- createFunction
- addNamedFunction
- createBool

This patch is part of the upstreaming effort from fir-dev branch.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D112057



Co-authored-by: Jean Perier <jperier@nvidia.com>
Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>