Add default value for maps:get
Enable tests
Add docs and test for maps:get/3
Test Tweaks
observer: Fix range check

Avoids wxWidgets assert if the table is empty
observer: Destroy the wx env

Ensure that the server exists on close, even though linked to the test process
observer: Let wx create statusbar

wx can not catch the delete of the status bar if
it have not created it, which might cause a crash.
Merge branch 'dgud/observer/tests/OTP-11949' into maint

* dgud/observer/tests/OTP-11949:
  observer: Let wx create statusbar
  observer: Destroy the wx env
  observer: Fix range check
  Test Tweaks
  Enable tests
stdlib: Fix indentation of maps doc
Merge branch 'saa/add_default_value_for_maps_get/OTP-11951' into maint

* saa/add_default_value_for_maps_get/OTP-11951:
  stdlib: Fix indentation of maps doc
  Add docs and test for maps:get/3
  Add default value for maps:get
Merge branch 'maint' of https://github.com/erlang/otp