nip19: fix shared nevents that are too long

There comes a point when the sharing a Nip19 mention becomes unwieldy
when there is too much TLV data. This patch features a naive approach to
making sure the relay portion of the TLV data doesn't contribute too
much data to the mention.

It adds a maximum number of relays that should be shared in the mention,
right now it is set to four.

Changelog-Fixed: Fix shared nevents that are too long
Lightning-address: kernelkind@getalby.com
Signed-off-by: kernelkind <kernelkind@gmail.com>
Reviewed-by: William Casarin <jb55@jb55.com>
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Models/ProfileModel.swift

@@ -13,6 +13,8 @@ class ProfileModel: ObservableObject, Equatable {
     @Published var relays: [String: RelayInfo]? = nil
     @Published var progress: Int = 0
     
+    private let MAX_SHARE_RELAYS = 4
+    
     var events: EventHolder
     let pubkey: Pubkey
     let damus: DamusState
@@ -161,6 +163,10 @@ class ProfileModel: ObservableObject, Equatable {
     func getRelayStrings() -> [String] {
         return relays?.keys.map {$0} ?? []
     }
+    
+    func getCappedRelayStrings() -> [String] {
+        return relays?.keys.prefix(MAX_SHARE_RELAYS).map { $0 } ?? []
+    }
 }