set use_docker to default to True (#1147)

* set use_docker to default to true

* black formatting

* centralize checking and add env variable option

* set docker env flag for contrib tests

* set docker env flag for contrib tests

* better error message and cleanup

* disable explicit docker tests

* docker is installed so can't check for that in test

* pr comments and fix test

* rename and fix function descriptions

* documentation

* update notebooks so that they can be run with change in default

* add unit tests for new code

* cache and restore env var

* skip on windows because docker is running in the CI but there are problems connecting the volume

* update documentation

* move header

* update contrib tests