feat: Separator component

### Prerequisites

- [X] I have read the [Contributing Guidelines](https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#creating-an-issue).
- [X] I agree to follow the [Code of Conduct](https://ionicframework.com/code-of-conduct).
- [X] I have searched for [existing issues](https://github.com/ionic-team/ionic-framework/issues) that already include this feature request, without success.

### Describe the Feature Request

A dedicated component to spontaneously create a separator, horizontal or vertical depending of usages. Something similar to items separator, but without needs to be in items group or something to make it, and a vertical variant.

### Describe the Use Case

Allows to split several parts of an app smoothly, without having to write a custom css

### Describe Preferred Solution

Ideally something really light, with just a `vertical` bool to switch to a vertical mod, and just an empty styled div I guess ? Taking children doesn't seems to be logic

### Describe Alternatives

Except a custom styled component, not really possible right now

### Related Code

_No response_

### Additional Information

Using an empty item needs to make some tricks to remove it's default height, that is verbose for a simple thing like that

Start by reviewing the existing items separator and the component patterns in Ionic Framework. Define the requested separator's horizontal default and its vertical boolean variant, then verify that it can split app content without requiring children or custom CSS.

Written by the indexing model from the issue text.