perf: optimize serialization of arrays of trivial D-Bus types (#340)

* Improve performance of std::vector<> per Issue #339.

* refactor: improve performance of vector serialization

---------

Co-authored-by: Plinio Andrade <plinio.andrade@oracle.com>
Co-authored-by: Stanislav Angelovič <stanislav.angelovic@protonmail.com>

src/Message.cpp

@@ -226,6 +226,11 @@ Message& Message::operator<<(const UnixFd &item)
     return *this;
 }
 
+void Message::appendArray(char type, const void *ptr, size_t size)
+{
+    auto r = sd_bus_message_append_array((sd_bus_message*)msg_, type, ptr, size);
+    SDBUS_THROW_ERROR_IF(r < 0, "Failed to serialize an array", -r);
+}
 
 Message& Message::operator>>(bool& item)
 {
@@ -318,6 +323,15 @@ Message& Message::operator>>(uint64_t& item)
     return *this;
 }
 
+void Message::readArray(char type, const void **ptr, size_t *size)
+{
+    auto r = sd_bus_message_read_array((sd_bus_message*)msg_, type, ptr, size);
+    if (r == 0)
+        ok_ = false;
+
+    SDBUS_THROW_ERROR_IF(r < 0, "Failed to deserialize an array", -r);
+}
+
 Message& Message::operator>>(double& item)
 {
     auto r = sd_bus_message_read_basic((sd_bus_message*)msg_, SD_BUS_TYPE_DOUBLE, &item);