Render experimental badges on attributes and render stability/experimental badges everywhere

[lmolkova]

Currently we show that attribute is stable:

• only in the registry (i.e. attributes in the semconv such as http have no indication of stability, but definitions in the registry have them)
• we don't show if attribute is experimental, but probably should

We should also consider making stability required property in the yaml attribute definition, so it's always crystal clear

[trisch-me]

this is done with latest build tools release 0.24.0 open-telemetry/build-tools#307