[flang] Update tco tool pipline and add translation to LLVM IR

tco is a tool to test the FIR to LLVM IR pipeline of the Flang compiler.

This patch update tco pipelines and adds the translation to LLVM IR.

A simple test is added to make sure the tool is working with a simple
FIR program.
More tests will be upstream in follow up patch from the fir-dev branch.

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

Reviewed By: kiranchandramohan, awarzynski, schweitz, mehdi_amini

Differential Revision: https://reviews.llvm.org/D117781



Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
Co-authored-by: Jean Perier <jperier@nvidia.com>
Co-authored-by: Andrzej Warzynski <andrzej.warzynski@arm.com>