- units from properties specified in ddsim_steer.py
   already are in G4units, so no conversion needed

DDSim,Meta: Fix formatting for dict

The ddsim --meta.runNumberOffset command-line argument doesn't work
correctly (and similarly for event number).

On a machine running

```
LSB Version:    :core-4.1-amd64:core-4.1-ia32:core-4.1-noarch
Distributor ID: Scientific
Description:    Scientific Linux release 7.3 (Nitrogen)
Release:        7.3
Codename:       Nitrogen
```

I do

```
. /cvmfs/sw.hsf.org/key4hep/setup.sh
```

The then command

```
ddsim  --compactFile $LCGEO/FCCee/compact/FCCee_o1_v05/FCCee_o1_v05.xml -G -N10 --outputFile out.edm4hep.root --meta.runNumberOffset 735001  2>&1|tee log
```

eventually crashes with the error

```
Geant4UI         INFO  +++ EventAction> Install Geant4 control directory:/ddg4/EventAction/
Traceback (most recent call last):
  File "/cvmfs/sw.hsf.org/spackages7/dd4hep/1.23/x86_64-centos7-gcc11.2.0-opt/q4qtg/bin/ddsim", line 25, in <module>
    RUNNER.run()
  File "/cvmfs/sw.hsf.org/spackages7/dd4hep/1.23/x86_64-centos7-gcc11.2.0-opt/q4qtg/lib/python3.10/site-packages/DDSim/DD4hepSimulation.py", line 368, in run
    e4Out.RunNumberOffset = self.meta.runNumberOffset if self.meta.runNumberOffset > 0 else 0
TypeError: '>' not supported between instances of 'str' and 'int'
 *** Break *** segmentation violation
```

The arguments are never converted from strings to integers.
The change here fixes this.

Allow users to add track user information to G4 tracks, which then moves to Geant4Particle for saving

Always use Geant4 units, as written out by ddsim root I/O

This adds the arguments `--gun.etaMin` and `--gun.etaMax`. If both
`thetaMin` and `etaMax` are specified, `etaMax has precedence.