[feature] Add current_diff_url to Edit page

[jonoff]

Is your feature request related to a problem? Please describe. Continuing request from https://github.com/dgtlmoon/changedetection.io/issues/1857, Add current_diff_url to Edit page to make it easier to identify

Describe the solution you'd like A clear and concise description of what you want to happen.

The edit template doesn't include the current URL in the top header, while other pages do. Example of the header space right above the tab list being blank:

If the edit template at https://github.com/dgtlmoon/changedetection.io/blob/9ce86a28353659d5c8baca8f7fb979161634f5d1/changedetectionio/init.py#L712

Included a similar line to the Diff page like this one: https://github.com/dgtlmoon/changedetection.io/blob/9ce86a28353659d5c8baca8f7fb979161634f5d1/changedetectionio/init.py#L1054

Then it'd be easy to see which URL is being edited like the diff page: