Support for native BPM CS aggregator

[JeanLucPons]

This PR adds support for native BPM aggregator.
It also include support for needed vector variable and bring an incompatibly with the tango native backend due to the new function attach_array() to be implemented. pyaml_cs_oa backend is already up-to-date.
Please merge #123 and tag to 0.2.1 before merging this PR.

type: pyaml.accelerator
facility: BESSY2
machine: sr
energy: 1.7e9
controls:
  - type: pyaml_cs_oa.controlsystem
    prefix: "pons:"
    name: live
data_folder: /data/store
arrays:
  - type: pyaml.arrays.bpm
    name: ORBIT
    elements:
    - BPMZ5D1R
    - BPMZ6D1R
devices:
- type: pyaml.bpm.bpm
  name: BPMZ5D1R
  model:
    type: pyaml.bpm.bpm_simple_model
    x_pos_index: 0
    y_pos_index: 1
    x_pos:
      type: pyaml_cs_oa.epicsR
      read_pvname: ORBITCC:rdPos
      unit: nm
    y_pos:
      type: pyaml_cs_oa.epicsR
      read_pvname: ORBITCC:rdPos
      unit: nm
- type: pyaml.bpm.bpm
  name: BPMZ6D1R
  model:
    type: pyaml.bpm.bpm_simple_model
    x_pos_index: 2
    y_pos_index: 3
    x_pos:
      type: pyaml_cs_oa.epicsR
      read_pvname: ORBITCC:rdPos
      unit: nm
    y_pos:
      type: pyaml_cs_oa.epicsR
      read_pvname: ORBITCC:rdPos
      unit: nm

from pyaml.accelerator import Accelerator

sr = Accelerator.load("bessy2bpms.yaml")
print(sr.live.get_bpms("ORBIT").positions.get())
print(sr.live.get_bpms("ORBIT").h.get())
print(sr.live.get_bpms("ORBIT").v.get())
print(sr.live.get_bpm("BPMZ5D1R").positions.get())
print(sr.live.get_bpm("BPMZ6D1R").positions.get())

15 Jan% 2026, 09:00:25 | WARNING | OA control system binding for PyAML initialized with name 'live' and prefix='pons:'
[[ 144.05649344  455.74660592]
 [  96.43369884 -529.71892797]]
[144.05649344  96.43369884]
[ 455.74660592 -529.71892797]
[144.05649344 455.74660592]
[  96.43369884 -529.71892797]

[gubaidulinvadim]

This looks fine to me. I think it will be good to specify in the docstring that by native backend we mean that the underlying Device / PV implement an array of positions for many BPMs. (If I understand this correctly). I would like if @gupichon will also confirm that it is ok to merge because we wanted to fix the version to be used at the workshop.

[JeanLucPons]

OK. It will be nice to update the native tango-backend before fixing release for the workshop otherwise orbit correction on the bessy VA will not be possible with main pyaml branch.

[gupichon]

Small error in the yaml test file a "/" is missing.

[gupichon]

Typo error