kv-cache : fix seq_rm with seq_id == -1 (ggml-org#15226)

* kv-cache : fix seq_rm with seq_id == -1

ggml-ci

* cont : iterate over streams

ggml-ci

context : perform output reorder lazily upon access after sync (ggml-…

…org#14853)

* context : perform output reorder after lazily upon access after sync

ggml-ci

* cont : add TODO