The instrumentation Registry contains information about available
instrumentation, facilitates discovery, installation, and configuration.

The Registry allows for instrumentation to avoid depending directly on a
specific SDK implementation.

The SDK depends on the Registry, the instrumentation Base class depends on the
Registry, and auto instrumentation libraries extend the instrumentation Base
class.

The motivation for decoupling the Registry (and by extension the
instrumentation) from a specific SDK implementation means that anyone can
implement their own OpenTelemetry API compatible SDK, and they could continue to
use community made instrumentation.