Move restricted_width_content_types to .theme file

[markconroy]

Closes #733

What does this change?

Moves the declaration of the restricted_widths_content_types from node--full.html.twig to localgov_base.theme so it's easier for subthemes to add to/remove from the array.

[finnlewis]

@tonypaulbarker would like to test this.

[markconroy]

@tonypaulbarker Any update on testing this? I'd like to get it accepted/rejected as soon as possible so I can keep working on the full view mode template for SDC.

[tonypaulbarker]

@markconroy half time report is this: I like the idea, I think it'll work, yet to carry out functional testing.

My early concern was for someone who has overridden the template in their sub-theme. Having examined the code I think it's going to be okay. If the array has been set in the template with a copy of the old code then those should still be the values used. And if the class isn't being used at all that's not a case we need be concerned about either.

[markconroy]

@tonypaulbarker Great stuff, thanks. Can you mark this as approved when you get a chance to finish your testing? Thanks.

[tonypaulbarker]

@markconroy it doesn't seem as though I have the permissions to approve this but approved subject to a check / remedy if needed of the two failing automated tests.

It seems events have been missing this class as they are using a specified template that doesn't set the variable. With the new code events do get the class. Not a blocker but worth noting for release notes.
I found some instances of content widths too narrow or too wide around the demo site already present and not related to this change. I'll file a new issue to look at those.

[markconroy]

Thanks @tonypaulbarker, that's merged now.