[CICD] Add workflow to benchmark all pallets (including external)

[sea212]

Currently we have to execute the complete benchmark of the runtime and include the result weights manually, whenever a release contains a codebase upgrade. We already have a workflow to only benchmark Zeitgeist pallets, but are missing one to benchmark every pallet, including external pallets. The benchmark should execute the script located at ./scripts/benchmarks/run_benchmarks.sh and commit the updated weights.