Fixes #69379

Fixes #71741

In cases where a webview takes a long time to be created, it is possible that we try applying styles to the unloaded iframe content. This happens when the load timeout fires before the window itself is actually created

Fix is to make sure we also apply styles in a DOMContentLoaded event handler

Make vscode-editor-font-family track real editor font family and introduce vscode-font-family for the UI font-family

Fixes #70619

**Bug**
`vscode-editor-font-family` was tracking the UI font family, not the actual `editor.fontFamily` setting

**Fix**
Make `vscode-editor-font` settings match the `editor.font*` settings

Introduce `vscode-font-*` settings that match the vscode ui settings

- is watching or not
- wait until provider is registered

fixes #71588