:telemetry public API in :membrane_core

[FelonEkonom]

The goal is to have a public API describing

• when membrane_core emits :telemetry events
• what are the types of these events
• what metadata is passed to each event

:telemetry events should allow writing the plugs that might be used for e.g. aggregating metrics, spans or structurized logs

What needs to be done:

• Take a look on how other open-source libraries or frameworks solve this problem (Phoenix, Ecto, Bandit, Finch, Oban etc.)
• Propose what :telemetry events are reasonably to be emitted from membrane_core
• What should be passed as the events metadata (proposition: pass there components state and create a public typespec describing the map that contains some fields from the state)
• Wrap emitting :telemetry events into macro, that will or will not be resolved to the :telemetry.execute(...), depending on config value (already partially/mostly done on the current master)