Add helper to add commonly used cli arguments

Writing this because I just got annoyed by it, and I will otherwise forget to at least write it down.

We have quite a few arguments that are commonly added. We could consider adding a few of them already pre-configured to the `parser` we can import from `parseArgs`. The most commonly used one is probably `--compactFile`. I have done

```python
from k4FWCore.parseArgs import parser

parser.add_argument("--compactFile", type=str, description="...")
```

countless times. I am fairly certain there are more of them. The simplest solution would be to either add a function `parser_with_default_args` that sets up these arguments already before users add theirs (possibly even configurable for "sets of arguments").

Alternatively for `compactFile` specifically we might consider adding it to `k4run` and in case it is present also inject the `GeoSvc` properly configured with it into the `ExtSvc`s of our `ApplicationMgr` (as we already do with some other services, I think).

Start by reading the k4FWCore.parseArgs entry point and inspecting k4run, especially how existing services are configured. Clarify whether the goal is a reusable set of default arguments or specific compactFile handling; done means one agreed approach is implemented and its argument and service behavior is covered by the project’s existing checks.

Written by the indexing model from the issue text.