[reland][flang] Add ETIME runtime and lowering intrinsics implementation (#92571)

This is same as https://github.com/llvm/llvm-project/pull/90578 with an
added fix. This PR updated tests of etime intrinsic due to Lowering
changes for assigning dummy_scope to hlfir.declare. Referring to
https://github.com/llvm/llvm-project/pull/92472 and
https://github.com/llvm/llvm-project/pull/90989