fix: do not show delegate button when address is not supported by the delegation network

[wa0x6e]

From #1051 (comment)

We currently allow delegating directly to an user, by prefilling the modal form with the user's address.

We should allow this only when the address is supported by the delegation network (on starknet delegation, only allow starknet address, and same for ethereum)

See this edge case with Nostra: https://snapshot.box/#/sn:0x07c251045154318a2376a3bb65be47d3c90df1740d8e35c9b9d943aa3f240e50/delegates