Event logger config takes instance instead of class (#7997)

* allow preconfigured event logger instance; deprecate specifying class

* add func docs and simplify conditions

* modify docs to reflect EVENT_LOGGER cfg change

* commit black formatting fixes and license header

* add type checking, fix other pre-commit failues

* remove superfluous/wordy condition

* fix flake8 failure

* fix new black failure

* dedent warning msg; use f-strings

docs/installation.rst

@@ -738,9 +738,9 @@ Example of a simple JSON to Stdout class::
                 print(json.dumps(log))
 
 
-Then on Superset's config reference the class you want to use::
+Then on Superset's config pass an instance of the logger type you want to use.
 
-    EVENT_LOGGER = JSONStdOutEventLogger
+    EVENT_LOGGER = JSONStdOutEventLogger()
 
 
 Upgrading