* postgresql_sequence: initial commit with new module and tests
* change return variables and adjust tests
* fix sanity checks
* fix linter errors
* change formatting functions and put params alphabetically
* add new examples and remove restrict option
* remove restrict option
* remove `required: false`
* add links to documentation
* change some minor parts in documentation
* add new integration tests for
** drop cascade
** change owner
* change usage of owner and created a test case for set owner during creation
* remove some documents and use docsfragments
* add aliases for minvalue and maxvalue
* change to warn if sequence not exists but should be removed
* use connect_to_db from module_utils/postgres.py
* add checkmode for several tests
* fix psycopg2 import and connect_to_db
* add a test for drop nonexistent sequence
* change get_info funcrtion to use only one SQL statement
* rewrite the module for cleaner code
* remove psycopg2
* change check_mode behavior
* add docstrings for class and methods
* add test for create sequence with owner in check_mode
* fix typo in set_schema()
* fix docu and cleanup the code
* adjust documentation for state, schema and newschema
* remove mutually_exclusive for 'absent'
* remove unused code comments
* remove warning for drop non-exicsting sequence
* change autocommit condition
* adjust state documentation
