Read Only properties don't set `readOnly` to true in thing description

[julianstirling]

Describe the bug
Some properties are read only. The only way to tell from the property's dataschema in the thing description is to check forms[0].op for readproperty. DataSchema defines readOnly and writeOnly. It would be good to also use those.

To Reproduce

check snake_workflow in the OpenFlexure Microscope Thing description, display_name is read only.

Expected behaviour
readOnly to be set.

System:

• OS: TD generated in CI
• Python version: 3.11
• Version: 0.0.14