* Add message while adding Oracle db connection
- Since UI currently doesn't have support for custom plugin names,
inform user to use the default plugin name for oracle
* Updated warning message
* Updated message
* alphabetize DB plugin types
* adds changelog
* add postgres to database plugins
* add statement fields
* adds tests for postgres db
* add delete confirm modal to db connection
* fixes text for confirmation modal - transform
* editing tests for delete modal
* fixes tests, oracle must be last DB tested
* adds test for modal and updates old modal tests
* creates serializer and moves available plugin types constant to util
* adds if block catch if no plugin_type, renames util file
* updates imports
* adds changelog
* fixes rendering of default attrs
* checks that plugin exists
