SusiDNS: Fix adding to empty address book

by doing form processing even if book is empty.
Do all form processing before displays so the
displays reflect any form add/delete.
Broken in 0.9.50 when form processing call was moved.
Hide replace and add alternate buttons if book is empty.
Ref: https://www.reddit.com/r/i2p/comments/wu7nac/how_do_i_add_to_the_private_address_book/