* implement events v1.32
implement the events api + sdk per spec v1.32:
- event logger is now only retrievable via an event logger provider
- domain attribute for events is removed
- events accept a subset of logrecord params, rather than an entire logrecord
* convert severity to a backed enum
* lint
* remove instead of deprecating logEvent, mark Logger constructor as internal
* make severity an enum only
* event attributes to iterable
* inject ClockInterface, add CachedInstrumentation, update examples
* set correct defaults for events
* test coverage
* Revert "make severity an enum only"
This reverts commit 710822907b.
Also, move PSR-3 mapping into the Severity enum.
* event attributes to iterable
* apply review feedback
Brett McBride
Tobias Bachert