core: group fixes/improvements (#7660)

* core: group fixes/improvements

* Large messages dropped by relays and hosts (the same 15602 limit was applied, without accounting for forwarding header)
* Members below v18 did not receive forwarded messages or history in p2p groups.
* Join confirmations near the size limit could fail.
* SMP servers are limited to 2 host names each.

* simplify

* remove legacy forwarding and history support

* only restrict p2p groups

---------

Co-authored-by: Evgeny @ SimpleX Chat <259188159+evgeny-simplex@users.noreply.github.com>

tests/MessageBatching.hs

@@ -33,6 +33,7 @@ import Simplex.Chat.Protocol
     GrpMsgForward (GrpMsgForward),
     MsgContent (MCText),
     VerifiedMsg (VMUnsigned),
+    fwdMemberName,
     maxBatchElementCount,
     maxEncodedMsgLength,
     mcSimple,
@@ -49,6 +50,7 @@ batchingTests = describe "message batching tests" $ do
   it "splits a batch that exceeds the element count limit" testBatchElementCountLimit
   it "does not create a relay delivery body when every task is oversized" testRelayBatchAllLarge
   it "classifies a task that fits raw but not as a framed singleton as large" testRelayBatchSingletonOverflow
+  it "shortens forwarded member names" testFwdMemberName
 
 instance IsString SndMessage where
   fromString s = SndMessage {msgId, sharedMsgId = SharedMsgId "", msgBody = s', signedMsg_ = Nothing}
@@ -190,6 +192,11 @@ testRelayBatchSingletonOverflow = do
   map deliveryTaskId accepted `shouldBe` []
   map deliveryTaskId large `shouldBe` [1]
 
+testFwdMemberName :: IO ()
+testFwdMemberName = do
+  fwdMemberName "sixteen_chars_ab" `shouldBe` "sixteen_chars_ab"
+  fwdMemberName "seventeen_chars_a" `shouldBe` "seventeen_chars_…"
+
 runBatcherTest :: BatchMode -> Int -> [SndMessage] -> [ChatError] -> [ByteString] -> Spec
 runBatcherTest mode maxLen msgs expectedErrors expectedBatches =
   it