Manage subscriptions front end

[TylerMatteo]

Create new page for managing subscriptions, pre-populated with existing user subscriptions:

• [ ] Create new page at route /subscribers/<id>
• [ ] Page implements designs found here
• [ ] Pre-populate checkboxes by querying for user's current subscriptions using the id route param.
• [ ] "Update" button should be disabled until selected subscriptions are different from existing values.

[pratishta]

@TylerMatteo Is sending users to the post-confirmation page part of the work for this ticket? https://www.figma.com/design/1HrOm1tkJ3lowQhrSRkPLs?node-id=678-385&m=dev#1030068624