Make GRT a separate step

[mleonowicz]

This PR introduces grt as a separate stage from route.

Now, stages may have multiple source stages instead of only one. This was needed, as the new route stage needs both congestion.rpt file, which comes from the grt route, and 4_cts.sdc file, which is produced by a cts stage.

Attaching before and after outputs produced by:
bazel query "deps(//:L1MetadataArray_generate_abstract)" --output=graph --noimplicit_deps --notool_deps > graph && xdot graph

[oharboe]

• Set GENERATE_ARTIFACTS_ON_FAILURE=1 variable for all stages in ORFS. This will set ORFS into a mode where it creates an artifact for a failed operation, such as ORFS so that e.g. a global route failure artifacts can be downloaded and studied.
• Rebase on main

[mleonowicz]

To support passing GENERATE_ARTIFACTS_ON_FAILURE = 1 argument to all stages, I have added a new argument to orfs_flow called common_args.

I have also rebased the branch.
@oharboe