v7.0.2

Networking: bump vendored MafiaNet to v0.8.0

Re-vendor MafiaNet from upstream tag v0.8.0
(commit 34d7472e458d00f5ec79a097afda5d0f3042983b), updating from
v0.7.0. No local patches; source matches upstream exactly.

Adds an optional disconnect reason to CloseConnection: a final
optional `const BitStream *reasonData` argument whose bytes are
appended right after the ID_DISCONNECTION_NOTIFICATION message ID,
so the remote peer can learn why it was dropped. The receiver reads
it from packet->data+1 (length packet->length-1). Only graceful
disconnects carry a reason; locally-synthesized notifications
(ID_CONNECTION_LOST, timeout/dead-connection) stay payload-less, so
consumers must tolerate a zero-length body. Wire-backward-compatible
and source-compatible: the new parameter defaults to nullptr, so
existing call sites (e.g. CloseConnection(guid, true)) are unaffected.

Also fixes RakPeer::CloseConnection no longer coercing an unresolved
target index (-1) to 0 and reading remoteSystemList[0], which
targeted an unrelated peer's slot or crashed on an unallocated list.