Clean state when removing plugin

[CremaFR]

In the current version, when removing a plugin, the state is not removed.
This could lead to unintuitive behavior, for instance:

A plugin with multiple signers is removed and re-added latter, all signers will be able to sign a for the acount, which for user coud lead to some confusion as when removing a plugin, one could expect the state to be cleaned.

Should we add a uninstall method to the plugin interface, to perform some state clean up, if necessary? Or manage this with a multicall (calls to clean the state with the last call to remove the plugin in the same transaction)

ps: I am aware for plugin like the sessionKey there is no solution to remove valid sessions on uninstall

[tarrencev]

Hmm yeah that's a good idea. We should add an uninstall method