Enable to add a new Group after first unsuccessful adding

[hstastna]

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1523214

Enable to add a new Group after first unsuccessful adding of the Group because
of missing Name, in Administrator > Configuration, Access Control tab > Groups.

---

Explanation:
The two simple conditions were added to prevent the error (see the BZ above), which was caused here:
https://github.com/ManageIQ/manageiq-ui-classic/blob/master/app/controllers/ops_controller/ops_rbac.rb#L1425
@edit[:new][:filter_expression] was nil, so the error occurred. It was set to nil here:
https://github.com/ManageIQ/manageiq-ui-classic/blob/master/app/controllers/ops_controller/ops_rbac.rb#L1252
The method rbac_group_set_record_vars is called right after the validation (see https://github.com/ManageIQ/manageiq-ui-classic/blob/master/app/controllers/ops_controller/ops_rbac.rb#L728) and even if it is not known if the validation was successful, the group record variables are set to new values, which is good only after successful validation (because of the if-else conditions in rbac_group_set_record_vars which are very specific). So the condition https://github.com/ManageIQ/manageiq-ui-classic/compare/master...hstastna:Add_Group_empty_name_validate?expand=1#diff-8078c760e06b820719715450b2a112e0R729 was added and also validation was extended by adding one simple line https://github.com/ManageIQ/manageiq-ui-classic/compare/master...hstastna:Add_Group_empty_name_validate?expand=1#diff-8078c760e06b820719715450b2a112e0R1424 to consider also the name of a new group.

This solution is simple and we don't have to reset variables @edit[:new][:filters] and @edit[:new][:filter_expression] (changed in rbac_group_set_record_vars method), if validation is not successful or if anything else breaks when creating/adding a new group (and we don't have to remember their values: we had to remember/save them, if we wanted to reset the variables after unsuccessful adding a group). And also none of the variables in the method are set (using fix in this PR) if rbac_group_validate? returns false, which is good. They are still set in the next try of adding a new group, after successful validation.

Before:

After:

[hstastna]

@miq-bot add_label bug, gaprindashvili/yes

[miq-bot]

Checked commit hstastna@76b8fa1 with ruby 2.3.3, rubocop 0.47.1, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 0 offenses detected
Everything looks fine. 🍰

[simaishi]

Gaprindashvili backport details:

$ git log -1
commit 937dfe5954b5c4ca1ec0d662337991ee23e47532
Author: Milan Zázrivec <mzazrivec@redhat.com>
Date:   Fri Jan 5 12:14:55 2018 +0100

    Merge pull request #3164 from hstastna/Add_Group_empty_name_validate
    
    Enable to add a new Group after first unsuccessful adding
    (cherry picked from commit 996a978c44f30a5fd0ed9db1268662963e953d87)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1531621