Segment anything button

From: https://github.com/developmentseed/ds-annotate/pull/13#pullrequestreview-1505859198

> Move the Segment Anything button to the sidebar and use a switch component instead, as it's just something to enable/disable a feature,

Sound good to move the button to the sidebar. If we employ a switch component, we'll have to decide how it behaves when activated. Should enabling the switch trigger a request to decode the view every time the map is clicked, or would it be better to have a separate button that sends the request only once when the switch component is turned on?

Currently, the app works as follows: if the site has cached an encoded image of the present map view, every click prompts a decode request. However, if there is no cached image, users still need to press the 'Segment Anything' button to encode the current map view. It's something we might want to reconsider as we make these changes.

cc. @willemarcel @rbavery