(Meta issue) Improve the post-comment experience for users

[JoannaHill]

Meta issue for the following related issues:

Develop Content to Improve Alert Failures Communication to Users #1723
#1694 by Sabina

Let commenters know what happened to the application
#557 by Henare

Improve comment guidelines
#1691 by Sabina

Invite users who left a comment to share whether they received a response from the council, and publish their feedback on Planning Alerts
#1696 by Sabina

Send users confirmation of their comment delivery
#1694 by Sabina

Set expectations with commenters and planning authorities to follow up after a comment is made
#1731 by Kat

Establish Clear Follow-Up Guidelines and Expectations for Commenters and Planning Authorities
#1730

#1477