[#62265] Advanced work package meeting selector

[mrmir]

Ticket

https://community.openproject.org/work_packages/62265

What approach did you choose and why?

• Add and use custom meeting autocompleter in the form
• Move grouping logic to GroupMeetingsService, so that everything is in one place for the meetings index page & the autocompleter
• Add 'Add to section' field to the form along with refresh logic to always update when a particular meeting is selected, using refresh-on-form-changes
• Add specs for all the automatic section selections

Merge checklist

• Added/updated tests
• Added/updated documentation in Lookbook (patterns, previews, etc)
• Tested major browsers (Chrome, Firefox, Edge, ...)