[bosh] Fix BOSH debug send message not shown
Following logcat are captured with various PR fixes implemented:
// ===== Without any of the PR fixes ===== //
All the sent stanza are missing; fixed by
```
// Fix all BOSH sent debug messages not shown
writer.flush();
```
```
2023-12-11 12:25:33.548 5470-5636/org.atalk.android D/SMACK: RECV (0):
<body xmpp:version='1.0' authid='4867162268865181478' xmlns='http://jabber.org/protocol/httpbind' sid='53e66759d21e128cc1cba8d00aacb7421f1ea960' wait='60' ver='1.11' polling='2' inactivity='30' hold='1' xmpp:restartlogic='true' requests='2' secure='true' maxpause='120' xmlns:xmpp='urn:xmpp:xbosh' xmlns:stream='http://etherx.jabber.org/streams' from='atalk.sytes.net'>
<stream:features>
<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
<mechanism>
PLAIN
</mechanism>
<mechanism>
SCRAM-SHA-1
</mechanism>
<mechanism>
X-OAUTH2
</mechanism>
</mechanisms>
<register xmlns='http://jabber.org/features/iq-register'/>
</stream:features>
</body>
2023-12-11 12:25:33.748 5470-5636/org.atalk.android D/SMACK: RECV (0):
<body xmlns='http://jabber.org/protocol/httpbind'/>
2023-12-11 12:25:33.925 5470-5636/org.atalk.android D/SMACK: RECV (0):
<body xmlns='http://jabber.org/protocol/httpbind'>
<challenge xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
cj1DI2QjJHE7JVs6LzElInQnPDhaK3JLMTUzPCtPVicvXmNuV204ei9kV1UzT1lsdCtzRW1ZTkE9PSxzPTdjNktCSnNaTHdTYjNZSytqdVRXb2c9PSxpPTQwOTY=
</challenge>
</body>
2023-12-11 12:25:33.939 5470-5636/org.atalk.android D/SMACK: RECV (0):
<body xmlns='http://jabber.org/protocol/httpbind'>
<success xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>
dj1saEFrUzVKMFRBMEJVbTg1djd5dE4xTUpZaE09
</success>
</body>
```
// ===== With only PR fixes: writer.flush(); readerConsumer = null; but withoug the following fixes ===== //
// Initialize the debugger before addBOSHClientResponseListener(new BOSHPacketReader());
// BOSHPacketReader may hold and send response prior to display of the request i.e. \<response/> before \<challenge/>
