Standard way to define device once that is shared between multiple end statations

It is common for branched beamlines to have shared components, e.g `PGM` is used by I06 and I06-1.

In dodal, we don't seem to have a standard way of doing this as of yet. At the moment, we have `dodal/beamlines/i05.py, dodal/beamlines/i05_1.py` and `dodal/beamlines/beamline_specific_util/i05_shared.py`. However, `i05.py` and `i05_1.py` both redefine the pgm which defeats the purpose were trying to achieve.

```Python
from dodal.beamline_specific_utils.i05_shared import pgm as i05_pgm

@device_factory()
def pgm() -> PGM:
return i05_pgm()
```

In other situations, we have I09 defined DCM in two different places when it's the same device `i09.py` and `i09_1.py`.

This should be defined once in it's own module. This seems to be what I19 have done with `i19_1.py`, `i19_2.py` and `i19_optics.py`, though I think this is slightly different use case as this is a way for access control and has its own BlueAPI service. However, I believe all beamlines, if has shared endstations, should have devices defined once in a shared module. This way, we get BlueAPI to pull devices from beamline `iXX` and `iXX_shared` to be into a single environment e.g

```
worker:
env:
sources:
- kind: planFunctions
module: sm_bluesky.beamlines.i05.plans
- kind: planFunctions
module: sm_bluesky.common.plan_stubs
- kind: planFunctions
module: sm_bluesky.common.plans
- kind: planFunctions
module: dodal.plans
- kind: dodal
module: "dodal.beamlines.i05"
- kind: dodal
module: "dodal.beamlines.i05_shared"
```

I think we can also go further and maybe define a `dodal/beamlines/core.py` as well because almost every beamline defines `Synchrotron` device, we can remove this duplication.

Finally, as this makes beamlines more modular and we want to test using `dodal connect iXX` for a whole beamline, I suggest the following change be made to dodal connect:

We define some config in dodal e.g

```Python
_BEAMLINE_SHARED = {
"i09": ["i09", "i09_1_shared", "i09_2_shared"]
...
}
```
This config defines the whole beamline so when running dodal connect i09, we get:

```
(venv) root ➜ /workspaces/dodal (fix_test_motor_limits_with_new_ophyd_async ✗)
$ dodal connect i09 -s
====================================================================================================
Attempting connection to i09 (using dodal.beamlines.i09)
2 devices connected (sim mode):
analyser_driver
synchrotron
====================================================================================================
Attempting connection to i09_1_shared (using dodal.beamlines.i09_1_shared)
1 devices connected (sim mode):
dcm
====================================================================================================
Attempting connection to i09_2_shared (using dodal.beamlines.i09_2_shared)
1 devices connected (sim mode):
pgm
```
We can also add a flag to test the individual beamline only

```
(venv) root ➜ /workspaces/dodal (fix_test_motor_limits_with_new_ophyd_async ✗)
$ dodal connect i09 -s -i
====================================================================================================
Attempting connection to i09 (using dodal.beamlines.i09)
2 devices connected (sim mode):
analyser_driver
synchrotron
```

## Acceptance Criteria
* Documentation added on standard for shared modules
* Beamlines conform to standard.
* Dodal connect command adjusted