Confirm removal of Trusted Publisher

[dgw]

What's the problem this feature will solve?

It is possible to accidentally delete a Trusted Publisher from a project with one click on the "Remove" button.

Describe the solution you'd like

Clicking "Remove" on a Trusted Publisher should confirm the action first.

Additional context

The "Archive project" button is the closest prior art in Warehouse's existing feature set that I know of:

Removing a Trusted Publisher also only requires a simple confirmation like this, without the added complexity of entering some value to confirm it like e.g. "Yank" (on a release) does.

The "Remove" button in question for Trusted Publishers is here:

warehouse/warehouse/templates/manage/manage_base.html

Lines 624 to 627 in 5fa4744

	<input form="delete-publisher-{{ publisher.id }}"
	type="submit"
	value="{% trans %}Remove{% endtrans %}"
	class="button button--danger">