Merge for v6.0.0

[estruyf]

✨ New features

• #193: Support added for editing data files.
• #197: Support for multi-dimensional content type fields on content creation and editing.
• #225: Placeholder support for front matter field values (template and content type).
• #226: Ability to specify the local server start command and trigger it from the UI.
• #227: Specify the file types to support with the new frontMatter.content.supportedFileTypes setting.
• #228: Show bulk button actions in panel and dashboard view.
• #231: Once you authenticate via GitHub as a supporter, the support links will be hidden from the UI.

🎨 Enhancements

• Added default field value for content type fields
• HMR support for panel webview development
• Added reveal media file action
• #187: Svelte support with the #227 features has been added.
• #198: Additional media sort options (alt, caption, and size).
• #230: JSON front matter support added.
• #233: Partial update when a page is updated.

🐞 Fixes

• #234: Fix for multi-word keywords
• #235: Fix for reselecting the previously removed value from a choice field