Create the hide note layer button when that layer is active

[Robot8A]

Description

Would solve #867 by adding a new button to hide the note layer just below the add note button. This button would only appear when the note layer is active. A user who activated the layer by clicking the add note button would expect a button to hide it in the vicinity of where they clicked.

How has this been tested?

Run locally via docker compose, open the locally hosted website in my browser.
Toggle the note layer via the layer panel, and the hide note layer button appears and disappears.
Click the add note button on the side, and the hide note layer button appears (as the note layer is activated).

Edit: Currently modifying the existing tests so they can handle the new functionality. I will remove the draft status when this is done.

Edit 2: Finally managed to get the tests to work correctly on my side. Removing the draft status.

[gravitystorm]

I don't think this is a good approach, for a few reasons:

• We have multiple overlay layers, which are shown in the layers menu. I know that it's not great UI as-is, but adding a button for just one of the layers is inconsistent
• There's some ambiguity here around activation state. When the button is in active mode (as shown), but the icon has a crossed out eye, it's not clear whether the button is to show the layer or to hide it.
• If we added such a button, it should be grouped with the other note button
• I think that it's too niche a problem to have the button showing all the time, but I also wouldn't want buttons appearing and disappearing.

So overall I don't think this is the answer.

[tomhughes]

This is better than #6890 but I agree with @gravitystorm that it's not really very nice.

I suspect the correct solution is along the lines of that originally proposed in #867 of having the note layer turn off once the panel is closed - possibly the new note alone should be left to address my concerns in #867 (comment)?

[gravitystorm]

@Robot8A Thanks for your suggestion, but based on the comments above we're going to decline this PR.