Metamask login: only supports first wallet, no detach/switch

[jamesacklin]

When attempting to swap a star held in a Metamask wallet, the user is blocked from disconnecting the wallet -- clearing cache does not help. The user is additionally blocked from choosing which Metamask address to use -- it is automatically connected to the last wallet without any way to unbind and select a new one.

Expected behavior
The user should be able to change Metamask wallets, even once connected.

cc @crrncllns