Toggle between default and custom editors

[sverg1]

Background

This is a subtask of #84520 involving a keybinding that toggles between the default editor of a file and its custom editor (if applicable). The goal is to add flexibility between different view modes without having to force views such as in the example below.

Example

Pertaining to the aforementioned parent issue in particular, one can force the custom Markdown preview mode by adding the following experimental setup to settings.json:

"workbench.experimental.editorAssociations": [
    {
        "viewType": "vscode.markdown.preview.editor",
        "filenamePattern": "*.md"
    }
]

Save-to-Preview

Using another keybinding, the user can save the file and switch to the custom editor all in one command. For example, saving in a Markdown file may automatically switch to its preview mode so that the user can see the final look of the file with each edit.

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Help test and implement the markdown custom editor preview (#84520)

[mjbvz]

This ended up being implemented as a single: editor.action.customEditor.toggle command