Make stability required, fix ref and extends, render badges on metrics

[lmolkova]

Follow up on #267 (comment)

See open-telemetry/semantic-conventions#763

This PR:

• requires stability on attributes and metrics
• allows to deprecate metrics
• allows to render stability/deprecation labels on metrics
• fixes stability and deprecation inheritance (there was no inheritance and according to semconvgen all attributes except their original definitions in the registry are experimental)

It would result in all metrics and attributes, referenced or declared to be able to have a badge (can turn on/off with cmd arg) - example with everything on:

Attribute	Type	Description	Examples	Requirement Level
test.deprecated_experimental_attr	boolean			Required
test.deprecated_stable_attr	boolean			Required
test.exp_attr	boolean			Required
test.stable_attr	boolean			Required

Name	Instrument Type	Unit (UCUM)	Description
stable_metric	Histogram	s	stable_metric

Name	Instrument Type	Unit (UCUM)	Description
experimental_metric	Counter	{e}	experimental_metric

Name	Instrument Type	Unit (UCUM)	Description
deprecated_metric	UpDownCounter	{d}	deprecated_metric

(PS: sorry for the huge PR, most of it is adding stability to all test data attributes 😴)