Add searchability to embed config

[TaiWilkin]

Overview

Edit embed field config to allow marking a field as searchable and
add model and API support for persistence.

Connects #1533

Demo

Notes

Adding the checkbox to the right of the fields input caused the draggability buttons to wrap to the next row on certain screen sizes. I adjusted the layout / breakpoints to move the embed code box above the fields list on smaller screen sizes.

The new text_search_label field has been added to the embed config model, but hasn't yet been added to the embed config page. See #1534 for next steps.

Testing Instructions

• Run ./scripts/manage migrate
• Run ./scripts/server
• Navigate to c2@example.com admin and login as c1@example.com. Set the embed level to Embed Deluxe / Custom Embed and save.
• Logout. Login as c2@example.com and navigate to contribute.
• Upload a list with extra fields and note the list ID in the url.
  oar-extra-fields.csv
• In vagrant, run (with the appropriate list-id):

./scripts/manage batch_process --list-id 16 --action parse
./scripts/manage batch_process --list-id 16 --action geocode
./scripts/manage batch_process --list-id 16 --action match

• Navigate to settings and select the Embed tab.
• Select several fields to be 'included', then check 'searchable' for them. Refresh the page and confirm they are still included and searchable.
• Uncheck the left checkbox for a field that is searchable and note that the 'searchable' checkbox is unchecked.
• Use 'select all' to uncheck all checkboxes and note that all searchable checkboxes are unchecked. Refresh the page to confirm persistence.
• At various page sizes, hover over the list items to confirm that the draggable buttons render appropriately.
• Further experiment with the embed config and field settings to confirm that the config page behaves as expected.

Checklist

• fixup! commits have been squashed
• CI passes after rebase
• CHANGELOG.md updated with summary of features or fixes, following Keep a Changelog guidelines

[caseycesari]

Two small things, but otherwise working well.

[TaiWilkin]

Thanks for the feedback! I've made the suggested style changes and it's ready for another look.

[lederer]

Nice improvements. Thank you. Added a couple more and then that should do it.

[caseycesari]

Looks good!

[TaiWilkin]

Thank you for all the great feedback!