Desktop: Support executing codemirror commands when using execCommand

[CalebJohn]

I was helping @tessus with something and it came up that this could be useful. And actually with the wording I think the previous behaviour was a bit confusing/wrong.

[laurent22]

Could you give an example of what was not possible before, and what's possible now? How will the editor commands be invoked?

[CalebJohn]

The exact case that inspired this change was adding the joinLines command to the context menu.

await joplin.commands.execute('editor.execCommand', {
    name: 'joinLines',
});

CodeMirror has a selection of commands that are typically bound to keys, but can also be called with codemirror.execCommand(name). These commands were previously inaccessible without using a contentScript. There is no change to executing codemirror functions, this just adds the ability to also execute commands.

A benefit of this is that will give plugin developers more power to control the codemirror editor without having to write a contentScript.

[laurent22]

Sounds good, and that would indeed be useful. I think it would be good to add some plugin documentation about this as it's a bit hard to discover. Maybe you could add a new section on top of JoplinCommand.ts (below the "Executing Joplin's internal commands" section) with an example? Also is there a list of the Code Mirror commands we support that we can point to?

[CalebJohn]

That's a good suggestion @laurent22 adding documentation was long overdue. It's done now, I didn't build the docs locally but they should be good to go.

[laurent22]

Looks good, thanks for the update and doc!