Limit pure proxy to the source chain

[xlc]

Currently relaychain and its common good parachains shares same address book which is useful. However this is unsafe for pure proxy. Pure proxy on exists on the creating chain. So if I created a pure proxy on Polkadot, I will also see it on Statemint, and it is tempting for me to use on Statemint as well and may end up locked fund on the pure proxy on Statemint.

I actually locked/lost 10 DOT by sending it from Polkadot to the collective parachain but selected a pure proxy account. So we should avoid having them displayed in the account selection input in the teleport dialog as well.

[jacogr]

How did you create the pure proxy and make it available? (Just ensuring that all the details are here, since we don't really have out-of-the-box pure proxy support in the apps UI)

[xlc]

Create it via extrinsic and add it like normal proxy. Yeah I guess this is an issue. The apps don't know if this is a pure proxy.

One solution is add UI support on pure proxy and annotate it in metadata. And for manual import, allow user to specify this is pure proxy.