[select] standardize shared popover props

[adidahiya]

Changes proposed in this pull request:

• ❌ BREAK: move MultiSelect2 popover ref prop
  • before: <MultiSelect2 popoverProps={ ref: ... }>
  • after: <MultiSelect2 popoverRef={...}>
• Add popoverContentProps for <Suggest2>, following up from [select] feat(Select2, MultiSelect2): popoverContentProps #5346
• Move shared props to a shared interface for DRYness

Reviewers should focus on:

No regressions

Screenshot

[blueprint-bot]

[select] standardize shared popover props

Previews: documentation | landing | table | demo