Convert content below hours grid to a widget area

[matt-bernhardt]

Why are these changes being introduced:

• As the Libraries have re-opened, there have been a number of changes
  to the currently-static-HTML content below the hours grid. In order to
  allow us to change this content more responsively as the organization
  evolves, this converts that static content into a widget area so that
  changes don't require code updates.

Relevant ticket(s):

• https://mitlibraries.atlassian.net/browse/uxws-1367

How does this address that need:

• This takes out the static content from page-hours-json.php and
  replaces it with a new sidebar area. As part of the deploy of this, I
  will create and populate a widget with the static content.

Document any side effects to this change:

• The actual markup around this content will change, but not in a way
  that will be visible to the user or a search engine.

How can a reviewer manually see the effects of these changes?

As I write this, the branch is currently not deployed anywhere - so if you have a local network you can look at it there. If not, then I'll be deploying this to staging once #353 is through code review.

Screenshots (if appropriate)

Here's the current production hours page...

Converting that "Locations without hours" block to a widget area will momentarily cause it to disappear (this is from staging, after deploying the branch and before creating the new widget)

After the widget has been defined (taking care to remove the bit about the Physics reading room that motivated this entire ticket), the page looks like this:

Todo:

• Documentation
• Stakeholder approval

Requires new or updated plugins, themes, or libraries?

NO

Requires change to deploy process?

NO

[jazairi]

I haven't confirmed this because I found myself going down an unintentional rabbit hole with my local WP environment, but the code looks good and the premise makes sense. Thanks for including such excellent detail in the PR.