Enable the 'Change task status' context menu to work in Source mode

[claremacrae]

⚠️ Please check that this feature request hasn't been suggested before.

• [X] I searched previous Ideas in Discussions didn't find any similar feature requests.
• [X] I searched previous Issues didn't find any similar feature requests.
• [X] I am only requesting a single feature. Multiple changes should be split into individual requests, with links between them.
• [X] I believe my requested feature will be generally applicable to other users, not just me: it is not uniquely tied to my personal workflow.

🔖 Feature description

Enable the 'Change task status' context menu to work in Live Preview mode

This was broken out from #2564, which requested it for both Source Mode and Live Preview. /CC @kickTiger

✔️ Solution

Figure how to show context menus in source mode.

❓ Alternatives

No response

📝 Additional Context

No response

[claremacrae]

When this is done, remember to update the checkboxes in https://publish.obsidian.md/tasks/Editing/Toggling+and+Editing+Statuses#'Change+task+status'+context+menu