Feature/search express entries

[broreece]

Fixes #1

Description

This PR allows adding express entities into the concrete 5 adaptor.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Checked existing search behaviour remains unchanged.
• Confirmed the search can now search for express entities specified in the config

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation/README.md/CHANGELOG.md
• I have checked my code and corrected any misspellings

Caution areas:

• Let me know if this approach is appropriate for the issue or if I should be looking at a different approach.
• Currently the express entity search result is rather vague (At least when I searched for just the express entity name) let me know if this is intended, you can see the example in the bottom screenshot.

Sceenshots:

New config fields for the express entities, NOTE if no handle is inputted instead of all express entities being shown like pages none are shown. If requested I can change this so all express entities are shown in this case.

Search result for the express entity:

[hissy]

It's better to set URL. Select target page from sitemap per an express entity.

[broreece]

@hissy I made the suggested update to use the target page of the express entity.

In order to show editors will need to add an express list that points to a detail page:

And then add the entry detail block on the provided page.

After which the search should correctly use the express entries url. Please let me know if this methodology was wrong here.