Remove deprecated code

[distantnative]

This PR …

Removed deprecated code

• Removed Server class alias
• Removed API model method page.next and page.prev
• markdown component: Removed $inline parameter. Use $options['inline'] instead.
• $kirby->kirbytext(): Removed $inlineparameter. Use$options['markdown']['inline']` instead.
• $kirby->markdown(): Passing a boolean as second parameter isn't supported anymore. Use $options['inline'] instead.
• Removed Cms\File::dragText(). Use $file->panel()->dragText() instead.
• Removed Cms\File::panelOptions(). Use $file->panel()->options() instead.
• Removed Cms\File::panelPath(). Use $file->panel()->path() instead.
• Removed Cms\File::panelPickerData(). Use $file->panel()->pickerData() instead.
• Removed Cms\File::panelUrl(). Use $file->panel()->url() instead.
• Removed Cms\Files::findById(). Use $files->find() instead.
• Removed Cms\ModelWithContent::panelIcon(). Use $model->panel()->image() instead.
• Removed Cms\ModelWithContent::panelImage(). Use $model->panel()->image() instead.
• Removed Cms\ModelWithContent::panelOptions(). Use $model->panel()->options() instead.
• Removed Cms\Page::dragText(). Use $page->panel()->dragText() instead.
• Removed Cms\Page::panelId(). Use $page->panel()->id() instead.
• Removed Cms\Page::panelPath(). Use $page->panel()->path() instead.
• Removed Cms\Page::panelPickerData(). Use $page->panel()->pickerData() instead.
• Removed Cms\Page::panelUrl(). Use $page->panel()->url() instead.
• Removed Cms\Pages::findById(). Use $pages->find() instead.
• Removed Cms\Pages::findByUri(). Use $pages->find() instead.
• Removed Cms\Site::panelPath(). Use $site->panel()->path() instead.
• Removed Cms\Site:panelUrl(). Use $site->panel()->url() instead.
• Removed Cms\User::panelPath(). Use $user->panel()->path() instead.
• Removed Cms\User::panelPickerData(). Use $user->panel()->pickerData() instead.
• Removed Cms\User:panelUrl(). Use $user->panel()->url() instead.
• Removed Panel\Document::customCss(). Use Panel\Document::customAsset('panel.css') instead.
• Removed Panel\Document::customJs(). Use Panel\Document::customAsset('panel.js') instead.
• Removed Cms\Server. Use Cms\Environment instead.
• Removed Toolkit\Str::isUrl(). Use Toolkit\V::url() instead.

Ready?

• Unit tests for fixed bug/feature
• In-code documentation (wherever needed)
• Tests and checks all pass

For review team

• Add changes to release notes draft in Notion
• Add to website docs release checklist (if needed)