Cli: parsing multiple times throws `AlreadySelectedException`

This issue has been fixed in commons-cli:1.3 project which sadly has not been released yet.
See https://issues.apache.org/jira/browse/CLI-183

This patch builds another list of options with no selected groups by default.

When commons-cli:1.3 will be released, we need to remove this patch.

Closes #7282.
Changed the plugin manager to use the new CLI infra

The plugin manager now uses the CLI infrastructure. As a conscequence its interface has changed (which is a breaking change for configuration maangement tools). The interface now is consistent across the different plugin command:

 - `plugin install [options] <plugin_name>`
 - `plugin uninstall [options] <plugin_name>`
 - `plugin list [options]`

 Also, renamed `plugin` test package to `plugins` to align with the main package
Tests, tests and tests... And Fix :)

Fix test 7152
Add TrustManager
Remove unused methods
Remove plugin manager
Update and refactor all tests
Fix class name