Refactored help string generation

Refactored code to generate configuration help strings into its
own private function. The motivation is to use the same function
to generate help strings for both configuration parameters
(existing functionality) and parameter groups (to be added).

Partial-Bug: #1395819

Change-Id: I2c0fd50d50081c633fb50e89eb8c6a84d948f7cc
add tests coverage for an oslo.messaging use case

This change adds tests to checks the behavior when an
option in two groups shares the same deprecated group.

oslo.messaging usage: https://review.openstack.org/#/c/120038/

Change-Id: I47b4fae15bc6f4581b513e9c10a564f4f4a88e2f
Fix wrong order of positional args in cli

Positional arguments were incorrectly parsed because instead of
original order there was an alphabetical.

This patch brings a positional field in Opt class and then sorts
all arguments by position-name.

Change-Id: Ia22654442b895c3f62834428f0ec6c3e8af22ebb
Closes-Bug: 1392428
Merge "Refactored help string generation"
Merge "Fix wrong order of positional args in cli"
Workflow documentation is now in infra-manual

Replace URLs for workflow documentation to appropriate parts of the
OpenStack Project Infrastructure Manual.

Change-Id: I93536c7f1d2f81b2619855dbc20014ea6eddd302