[lldb-dap] start all sent protocol message from number one. (#170378)

This aligns with the DAP
[specification](https://microsoft.github.io/debug-adapter-protocol//specification.html#Base_Protocol_ProtocolMessage)

Force it to be an error in test cases.

lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py

@@ -391,7 +391,7 @@ class DebugCommunication(object):
         with self._recv_condition:
             for packet in self._recv_packets:
                 if packet and ("seq" not in packet or packet["seq"] == 0):
-                    warnings.warn(
+                    raise ValueError(
                         f"received a malformed packet, expected 'seq != 0' for {packet!r}"
                     )
                 # Handle events that may modify any stateful properties of

lldb/tools/lldb-dap/DAP.cpp

@@ -274,8 +274,11 @@ Id DAP::Send(const Message &message) {
   std::lock_guard<std::mutex> guard(call_mutex);
   Message msg = std::visit(
       [this](auto &&msg) -> Message {
-        if (msg.seq == kCalculateSeq)
-          msg.seq = seq++;
+        if (msg.seq == kCalculateSeq) {
+          seq++;
+          msg.seq = seq;
+        }
+        assert(msg.seq > 0 && "message sequence must be greater than zero.");
         return msg;
       },
       Message(message));

lldb/tools/lldb-dap/Protocol/ProtocolBase.h

@@ -31,11 +31,11 @@ namespace lldb_dap::protocol {
 // MARK: Base Protocol
 
 /// Message unique identifier type.
-using Id = int64_t;
+using Id = uint64_t;
 
 /// A unique identifier that indicates the `seq` field should be calculated by
 /// the current session.
-static constexpr Id kCalculateSeq = INT64_MAX;
+static constexpr Id kCalculateSeq = UINT64_MAX;
 
 /// A client or debug adapter initiated request.
 struct Request {