[V2V] Conversion host base class

[djberg96]

When creating a conversion host, we want to set the resource_type to the base class name of the resource rather than the subclass. Setting it to the subtype can break polymorphic associations, as it did for ExtManagementSystem.

Fixes #18603

On an unrelated note, I had to add an explicit require 'resolv' to the top of the file because it started breaking without it. It's actually part of the stdlib, but something must have changed in the load ordering.

https://bugzilla.redhat.com/show_bug.cgi?id=1695797
https://bugzilla.redhat.com/show_bug.cgi?id=1693378

[miq-bot]

Checked commits https://github.com/djberg96/manageiq/compare/6ced3c91f1079881af77f6998ec4ee64b88dea65~...f9a16568d6d90f0c65db235ed48454c37fa06f92 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
3 files checked, 0 offenses detected
Everything looks fine. ⭐

[ghost]

@miq-bot add-label transformation, hammer/yes

[ghost]

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1693378

[simaishi]

Hammer backport details:

$ git log -1
commit 0226e358532b87305da181aaae72d9853d4034df
Author: Adam Grare <agrare@redhat.com>
Date:   Thu Mar 28 20:44:55 2019 -0400

    Merge pull request #18604 from djberg96/conversion_host_base_class
    
    Conversion host base class
    
    (cherry picked from commit 799d2c5992ae6a9a13931dbd7213c540007c1458)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1696437
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1696447