WIP: stage-main for Spoke 5.6/6.0

[schuyler1d]

Pull Requests (so far)

• Show contact upload progress with contact loaders #1531
• Replace old texter ui with new one with env var: DEPRECATED_TEXTERUI=GONE_SOON #1506 (also covering User canned response deprecation https://github.com/MoveOnOrg/Spoke/issues/1523)
• Add title to campaign edit #1500
• [1362] Feature Request: Change the label on the "Send Replies" button #1489
• AssignmentTexter refactor #1534 (as part of RFC RFC: Request/Release-style dynamic assignment + Texter Sidebox extensibility #1533)
• Paginated, searchable people page with other enhancements #1345
• 🚧 WIP Complete Action Handler Framework #1540
• Preserve Question Responses created_at across updates. #1542
• Add permissions checks to importCampaignScript and updateQuestionResp… #1521
• Required text inputs on the campaign basics tab #1561
• Remove CampaignContact.questionResponses #1551

Testing:

• @JeremyParker Migration To Add Roles VETTED_TEXTER, ORG_SUPERADMIN, SUSPENDED #1554
• @matteosb Stage phone number management and campaign messaging service changes #1557

Expected soon:

• @lperson with a full version of action_handler api changes (Preserve Question Responses created_at across updates. #1542)
• @matteosb upgrading Apollo-client to 2.x (will affect a lot of containers/ files)
• @schuyler1d and campaign schema changes related to RFC RFC: Request/Release-style dynamic assignment + Texter Sidebox extensibility #1533

Draft Release Notes

We're marking this as a major version update: 6.0 because there are several backwards-incompatible changes, but we think you will love them:

• Campaigners: There is a new Texting UI -- in version 5.6 it was enableable with EXPERIMENTAL_TEXTERUI ahead of time. It is now the default! For this version, we allow you to preserve the old texter UI by setting the environment variable DEPRECATED_TEXTERUI=GONE_SOON. Also note that with the new UI we have removed user-created Canned Responses -- there's consensus that it causes more problems than it helps. We've also long had the Super Volunteer role which most campaigns use for a group of texters that can update canned responses when needed.
• (TBD) Action Handler developers: Through the great work of @lperson for improved VAN support, our action handler api used to return a true/false value for the available() call -- it should now return an object with two keys: { result: <boolean on available>, expiresSeconds: <how long to cache the result, 0 by default>}
• There are several schema changes -- only adding fields, so migration should be easy/fast. However, if you have SUPPRESS_MIGRATIONS enabled, then you will need to manually migrate the database ( Heroku, AWS Lambda )

In addition to those changes, we've improved the Admin People page (@lperson ) and made some tweaks to the Campaign Edit page (@matteosb , @higgyCodes ), and the Texter Todo list (@larkinds ).