Add order option to SupportsFeatureMixin module

[djberg96]

This is a followup (or prequel?) to #19186 that would allow the ability to set whether or not a given service is actually orderable.

At the moment there's only ServiceTemplate.validate_order which returns a simple boolean. This allows for more flexibility for subclasses/providers that can hook into it and provide custom messages if/when it's not supported.

Update: This also explicitly includes the SupportsFeatureMixin into the ServiceTemplate class, and adds a default supports :order to it.

[djberg96]

@miq-bot add_reviewer @agrare

[agrare]

@djberg96 can you add the first supports :order to ServiceTemplate in this commit so it doesn't look like there's an unused feature?

[djberg96]

@agrare Done.

[agrare]

👍 nice, looks good @djberg96

[miq-bot]

Checked commits https://github.com/djberg96/manageiq/compare/a73a816e5e94ca7b01cca40af3c1c72946f80475~...69684c2978dd8d6b231facdf0b10db8837203016 with ruby 2.4.6, rubocop 0.69.0, haml-lint 0.20.0, and yamllint 1.10.0
3 files checked, 0 offenses detected
Everything looks fine. 🏆

[simaishi]

@djberg96 can this be ivanchuk/yes?

[simaishi]

@djberg96 ^ ping

[djberg96]

@simaishi Pretty sure, yes. @agrare Do you have any objection?

[agrare]

Fine with me

[simaishi]

Ivanchuk backport details:

$ git log -1
commit ac4757e1ad3235aa09516f2c03464c6c0b9f6edd
Author: Adam Grare <agrare@redhat.com>
Date:   Mon Aug 26 15:55:19 2019 -0400

    Merge pull request #19203 from djberg96/supports_feature_order
    
    Add order option to SupportsFeatureMixin module
    
    (cherry picked from commit baeb7ba143c811e402f8507c386fc669efabf527)
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1768520