Qblox backend refactor: move io-processing helper functions to backend (QAE-1229)

Explanation of changes

• Delete output_name_to_outputs and input_name_to_inputs functions and move their io_name-tuple dicts to StaticHardwareProperties as io_names_to_connected_ios (naming open to suggestions).
  • Move get_io_info as a private method of StaticHardwareProperties (method open to modifications e.g. retrieve connected ios somewhere else and rename to get_io_mode).

Extra change:

• Refer to io indices as "connection indices" in docstrings (there are already acquisition indices).
• Substitute io_mode string literals by IoMode enums.

Motivation of changes

The io-processing helper functions get_io_info, output_name_to_outputs and input_name_to_inputs are used to retrieve static only useful for the backend, so they should not be part of the public interface.

---

Merge checklist

See also merge request guidelines

• Merge request has been reviewed (in-depth by a knowledgeable contributor), and is approved by a project maintainer.
• New code is covered by unit tests (or N/A).
• New code is documented and docstrings use numpydoc format (or N/A).
• New functionality: considered making private instead of extending public API (or N/A).
• Public API changed: added @deprecated (or N/A).
• Tested on hardware (or N/A).
• CHANGELOG.md and AUTHORS.md have been updated (or N/A).
• Windows tests in CI pipeline pass (manually triggered by maintainers before merging).
  • Maintainers do not hit Auto-merge, we need to actively check as manual tests do not block pipeline

---

For reference, the issues workflow is described in the contribution guidelines.