Call ensure_connected on all ophyd_async devices

[DiamondJoseph]

Fixes #864

Instructions to reviewer on how to test:

1. Run dodal connect i22 while on the network and able to get those PVs
2. Ensure that devices are connected
3. Change the PV prefixes of some devices on i22 to known invalid values
4. Ensure that dodal connect i22 does not connect to those devices

Checks for reviewer

• Would the PR title make sense to a scientist on a set of release notes
• If a new device has been added does it follow the standards
• If changing the API for a pre-existing device, ensure that any beamlines using this device have updated their Bluesky plans accordingly
• Have the connection tests for the relevant beamline(s) been run via dodal connect ${BEAMLINE}