Enable to add tag for configuration provider

[hstastna]

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1549488

Enable to add tag for configuration provider from 'All Rad Hat Satellites
Providers', in Configuration > Management > Providers accordion.

Important: the problem in the screen occurs right AFTER clicking on Save button in tagging screen, so it means that tagging screen opens without problems, it is possible to edit tags in the screen, but not to save them properly.

---

Before: (right after saving tags)

Original screenshot from the BZ, for better understanding/reproducing the problem:

After:

Details:
If we go to Configuration > Management > Providers accordion, we are normally on root node, it is All Configuration Manager Providers node, in the tree. After selecting some provider(s) in the list and clicking on Edit Tags (under Configuration), we are able to tag the provider and save the changes we made, without any problems. During this process (saving the tags), we enter class_for_provider_node method in provider foreman controller, which returns ManageIQ::Providers::ConfigurationManager. So we know that this works, when tagging a provider. BUT if we enter other node in the tree, for example All Red Hat Satellites Providers or Foreman Providers node (as in my screenshots above), we are no longer on root node so class_for_provider_node returns wrong class (but only when saving tags; ). It looks like it has never worked with that class. If we just enter tagging screen (after clicking on Edit Tags), tagging_edit method gets different db as an argument, comparing to what it gets when saving the tags!

[hstastna]

@miq-bot add_label bug, gaprindashvili/yes

[miq-bot]

Checked commit hstastna@abd869f with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 0 offenses detected
Everything looks fine. 👍

[ZitaNemeckova]

Tested in UI. LGTM 👍

[himdel]

This will be a bug if we ever decide to support other ConfigurationManagers than Foreman.

But for now, it does fix a bug :) and does not introduce breakage I can see..

[hstastna]

@himdel You are right, but also we are in provider foreman controller which cares about everything under Configuration > Management so.. if we ever decide to support other ConfigurationManagers than Foreman, we should also rename the controller and change many more things.

[simaishi]

Gaprindashvili backport details:

$ git log -1
commit d0f01699e68de4a636c573670ef5a48259be911f
Author: Martin Hradil <himdel@seznam.cz>
Date:   Fri Mar 9 12:36:19 2018 +0000

    Merge pull request #3528 from hstastna/Unable_add_tag_configuration_provider
    
    Enable to add tag for configuration provider
    (cherry picked from commit db62fc90bcc1f5057cf74c8923f3a2e9d31b5b8e)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1553789