[tech-debt] migrate datepickers to use the new component

The new datepicker is neat, and we should use it everywhere we can. This issue is to track the places it is not yet.

- [ ] Spending analysis report
- [ ] Formula report queries
- [ ] Custom report
- [x] Budget automations (https://github.com/actualbudget/actual/pull/8515)
- [ ] Date filter (revamp to support both day and month mode)

Use the checklist in the body as the implementation scope: Spending analysis report, Formula report queries, Custom report, and Date filter. Start by locating the current datepicker components used in those UI areas and identify which ones are still old. Use the Budget automations migration linked in the issue (PR 8515) to match the expected replacement pattern, then update each remaining area and confirm it now uses the new datepicker so all unchecked items are effectively completed.

Scritto dal modello di indicizzazione a partire dal testo della issue.