closes https://github.com/TryGhost/Product/issues/4015
Swapped `<KoenigBasicHtmlInput>` for `<KoenigLexicalEditorInput>`
- added support for passing `class` through to the container `<div>`
- updated caption handler to clean HTML and strip/add surrounding `<p>` as necessary
- added passthrough for `onFocus` prop
- updated styles to force font style inheritance within Koeing's `.kg-prose` class
refs TryGhost/Team#3008
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### <samp>🤖 Generated by Copilot at f785fd8</samp>
This change adds a new component `koenig-lexical-editor-input` that
renders a React component using the `@tryghost/koenig-lexical` package,
which provides a new editor for Ghost that supports rich text and
markdown editing. The component can be used to edit HTML content using
the Lexical editor, and syncs the HTML content with the `html` argument
and the `onChangeHtml` callback. The component also handles dynamic
import, loading, error, and dark mode scenarios.
