Dehydrated devices: Add some stuff to the crypto dev tools

We should consider adding some information about the state of dehydrated devices to the crypto dev tools (see https://github.com/element-hq/element-web/pull/29073), like:
* do I have a dehydrated device? - same logic as https://github.com/element-hq/element-web/issues/29264 is there a dehydrated device in the devices list?
* does the key for that device exist in 4S?
* do I have the key to the dehydrated device? - do we have the key cached?
* when is the dehydrated device scheduled to be rotated?

(Context: dehydrated devices are created often, e.g. when you refresh the tab, and each time one is created, the old one is deleted.)

Tasks:
* js-sdk should remember the timer it set for rotation of the device so it can display it
* Expose this information, which is known inside js-sdk, to element web
* UI to display the above info (no design needed because this is a dev tool)