feat(picker-column): add prefix and suffix slots (#28603)

Issue number: Internal

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## What is the current behavior?
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The new picker component does not have a counterpart for the `prefix`
and `suffix` properties on the old picker column.

## What is the new behavior?
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this PR. -->

- `prefix` and `suffix` slots added.
- Picker items wrapped in a new `.picker-opts` element for positioning
purposes, similar to the legacy picker column. This necessitated
additional changes to functionality and styling, since previously the
items were direct descendants of the host.
- New `setFocus` method added. This gets around a browser bug in Firefox
where calling `focus()` on the column doesn't correctly move focus, as
the nearest focusable element (`.picker-opts`) is in the shadow DOM.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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and migration path for existing applications below. -->

While you can no longer call `focus()` on the column in Firefox and must
use `setFocus()` instead, this isn't considered a breaking change
because this component isn't public API yet.

## Other information

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screenshots of how the component looks before and after the change. -->

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Co-authored-by: ionitron <hi@ionicframework.com>