[fir] Add external name interop pass

Add the external name conversion pass needed for compiler
interoperability. This pass convert the Flang internal symbol name to
the common gfortran convention.

Clean up old passes without implementation in the Passes.ts file so
the project and fir-opt can build correctly.

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

Reviewed By: schweitz

Differential Revision: https://reviews.llvm.org/D111057