I have observed that Syncthing Tray can get stuck thinking a remote device
still needs data. Likely the update got lost. The code contains certain
conditions in which folder completion events and requesting completion are
supressed. Those conditions are based on timestamps. That is not ideal as
the accuracy is only one second (so different timestamps might be
considered equal as they are rounded to be the same). Additionally, it
makes no sense to assume a timestamp upon receiving a response as the
information might be older than the time it was received.
This change avoids those conditions. It rather uses the event ID to
decide what event/reply is newer.
This change also uses quint64 instead of int for event IDs to avoid running
into an overflow (or rather conversion error) when deserializing the ID
which might be bigger than int. (Not sure how big the ID can become; this
is to be on the safe side.)
Fixes the following error
```
qdbusxml2cpp: Got unknown type `a{sv}' processing '/build/static-compat-syncthingtray/src/syncthingtray/syncthingconnector/org.freedesktop.DBus.Properties.xml'
You should add <annotation name="org.qtproject.QtDBus.QtTypeName.Out1" value="<type>"/> to the XML description for 'changed_properties'
```
by following the suggestion of that error. Not sure why this
error occurs only now. Maybe `qdbusxml2cpp` changed in Qt 6.5.0.
* Check directly whether changed properties contain a property
instead of checking indirectly whether the returned QVariant
is invalid.
* Avoid copying the QVariant.
* Effectively this should not change anything; the code is just
more readable and possibly more efficient.
Not sure why `QString::toStdWString()` doesn't work with this compiler and
the official Qt 6.5.0 build. However, instantiating an `std::wstring`
manually works so let's just use this as a workaround.
Note that with GCC/mingw-w64 and Qt 6.4.3 the `QString::toStdWString()`
function works just fine.
Martchus