Add: signup_notes, rename rider_notes.

[teesloane]

Describe your changes

Follow up to the closing of #340 , closes #385

This was done so that we could include signup related information when riders signup for a delivery.
It has also been on the backlog to rename "rider_notes" to "delivery_instructions"

Delivery Instructions - To be shown when a rider is doing a delivery. Sometimes contains personal information (ex: "Francis is hearing impaired and might not hear when you ring the doorbell."

Signup Notes - Instructions specific to choosing what to sign up for - for example: "{recipient A} is in the same building as {recipient B} - if you can signup for both that would be awesome!

Screenshot

CleanShot.2024-06-07.at.12.52.48.mp4

Product Update

"Hi Dispatchers! It is now possible to include "rider signup notes—these will show on the page where a rider assigns themselves a specific delivery. This might be useful for letting riders know about co-located deliveries, for example. Please avoid adding personal identifying information into the rider signup notes."

Checklist before requesting a review

• I have performed a self-review of my code
• If it is a core feature, I have added tests.
• Are there other PRs or Issues that I should link to here?
• Will this be part of a product update? If yes, please write one phrase
  about this update in the description above.

[mveytsman]

Looks great!