Don't run 'exec_action' blindly.
Fix jinja search path for local file_client

Now that FS backends other than roots work with a local file_client,
there is no need to look only in the file_roots directories.

Fixes #17963.
Add support for 'parameter' where appropriate.
Only return cleaned-up module names.

- strip module descriptions
- strip indentation from list output
- strip internal modules (help, usage, version)
Strip additional output from targets, return only actual targets.
Added 'parameter' to CLI examples.
Deprecate 'parameter' in favour of 'module_parameter'/'action_parameter'.

A generic 'parameter' argument doesn't cover what's actually required.
In some cases, parameters need to be passed either to the executed
module, action or both.

This changes gracefully deprecate the old 'parameter'.
Handle 'target' + 'action_parameter' in 'set_target()' correctly.
Documentation improvements for get_modules() and get_target_list().
Be a bit more careful with the results of 'exec_action()' and also sanitize them a bit.

In case the 'exec_action()' call for 'get_target_list()' returned no
results, because there were no available targets, the module would
stacktrace.
Documentation improvements for 'get_current_target()'.
Handle '(unset)' as return value (when no target is set) in get_current_target().
Documentation improvements for 'set_target()'.
Documentation improvements for 'exec_action()'.
Don't try to run blindly non-existent modules.
Fix logic error introduced sometime in the past 6 months that prevented all modules from being loaded.
Documentation improvements for 'set_()'.
No exceptions in execution modules.
Pylint.
Remove deprecated options