Render accounts if signer disconnected when in expanded view

[goosewobbler]

If you disconnect a signer when in expanded view the current behaviour is to render null - we should render the accounts.

[mholtzman]

I don't think we want to render the accounts in the signer view, this will mess up the navigation. probably it's better to just navigate back to the main accounts panel if a signer is removed

[mholtzman]

I think this implementation will still cause the "back" button from the account screen to go back to the signer. maybe @floating has a better idea of how the nav works specifically but I think the idea here is when we remove a signer (most likely in the Signers module) we also remove any nav related to that signer from the stack so that the view will naturally go back

[goosewobbler]

@mholtzman something like navClearReq but for signers?

EDIT: prototyped, looking at tests