Verify cast to int in V13Database.getTransactionIdBuffer

[mrotteveel]

The cast to int in V13Database.getTransactionIdBuffer is suspicious, it probably shouldn't be there. Also consider using a different method for encoding to remove the overhead of allocating a ByteArrayOutputStream and an extra byte array.

[mrotteveel]

Essentially, reconnect transaction on Firebird 3.0 and higher did not work for transaction ids exceeding 0x7FFF_FFFF (for JNA it probably did work, although I revised a range check there as well). For Jaybird 6, I also cleaned up the code and used the same code path for all AbstractFbDatabase sub-classes.