refs https://github.com/TryGhost/Team/issues/1290
- renamed `@updateExcludedEvents` to `@onChange` and updated associated action name so we have consistent naming for our select-like components
- added `<MembersActivity::MemberFilter>` component
- utilises `<PowerSelect>` with a custom trigger component and and a debounced search via the member's API
- does not use `<PowerSelect>`'s default "selected" behaviour in favor of replacing the select with a button to provide a clearer "reset filter" UX that's easier to build/style outside of the power-select components
- added `.ember-power-select-trigger-reset` class to reset margins, paddings, borders, and heights so that it's easier for a custom trigger's contents to control the display
98eb75ef06