Add support for exporting and importing widgets

[branic]

These rake scripts and classes provide functionality for exporting/importing of the following ManageIQ object types:

• Widgets

This PR uses the framework that was implemented for PRs #14126, #15256, #16717, and others to export/import other ManageIQ object types.

These scripts are based on the CFME RH Consulting Scripts and are used by Red Hat consultants to enable storing customizations in Git and maintaining customizations between environments (e.g. dev/qa/prod) for an SDLC lifecycle.

Links [Optional]

• Tracking Issue: Implement export/import functionality of Miq objects via command-line

Steps for Testing/QA [Optional]

Exporting

1. Create a directory for the exports

mkdir /tmp/widgets

2. Export user defined widgets

vmdb
bin/rake evm:export:widgets -- --directory /tmp/widgets

Importing

1. Import all widget yaml files in a directory

# vmdb
# bin/rake evm:import:widgets -- --source /tmp/widgets

2. or Import specific widget yaml file

# vmdb
# bin/rake evm:import:widget -- --source /tmp/widgets/Test_Widget.yaml

[branic]

/cc @gmcculloug @gtanzillo

[miq-bot]

Checked commit https://github.com/branic/manageiq/commit/9478c4f00c084c4f3e158c93fe1f7f0d4d73c8e4 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
5 files checked, 0 offenses detected
Everything looks fine. 🍰

[gtanzillo]

Looks good. Thanks @branic