Add a way to deprecate attributes of rules

### Description of the problem / feature request:

Sometimes it is desirable to be able to deprecate certain attributes of a rule, currently there is no way to do that.

### Feature requests: what underlying problem are you trying to solve with this feature?

I want to deprecate an attribute.

### Have you found anything relevant by searching the web?

No.

### Any other information, logs, or outputs that you want to share?

No.

The issue names no files, tests, or entry points. Start by tracing how rule attributes are declared and how deprecation is handled elsewhere in the project, then clarify the expected behavior for deprecated attributes. Done should include an agreed design, implementation scope, and tests covering the deprecation behavior.

Written by the indexing model from the issue text.