Messages page: updates to Previous Messages table

See https://github.com/lookit/lookit-api/issues/1498#issuecomment-2660054525

The following updates are needed for the "Previous Messages" table on the Message Participants page.

• Add show/hide column button for "Message Type" and "Child IDs" (or for all columns if implementation is easy)
• Re-size columns to make better use of space, using up to two lines per row and cutting off anything else with ellipses after that. (E.g. Date Sent column could be narrower, with date on one line and time on the other).
• In "Recipient" column, just list the hashed ID + name (remove UUID).
• Add a new "Child IDs" column with the child ID (hashed ID + name). When the message is sent by a researcher, the column value should include any children that are associated with the participant account AND a response session exists for that child. For CHS automated emails, this column will contain the IDs of any eligible children.
• Add some kind of tooltip or help text about the Child IDs: see this comment.

Edit: "Message Type" column removed because we do not currently store that info in our database. Moved to a separate issue. Ignore the "Message Type" column in the mock-up below.