[Core] Factor out common code in SequenceData and Sequence (#8675)

tests/test_sequence.py

@@ -1,10 +1,7 @@
-from array import array
-
 import pytest
 
 from vllm.model_executor.layers.sampler import SamplerOutput
-from vllm.sequence import (VLLM_TOKEN_ID_ARRAY_TYPE,
-                           CompletionSequenceGroupOutput, SequenceData,
+from vllm.sequence import (CompletionSequenceGroupOutput, SequenceData,
                            SequenceOutput)
 
 from .core.utils import create_dummy_prompt
@@ -58,7 +55,7 @@ def test_sampler_output_eq(sample_outputs):
 
 
 def test_sequence_data_prefill():
-    seq_data = SequenceData(array(VLLM_TOKEN_ID_ARRAY_TYPE, [1, 2, 3, 4]))
+    seq_data = SequenceData.from_seqs([1, 2, 3, 4])
     assert seq_data.get_num_uncomputed_tokens() == 4
     assert seq_data.get_num_computed_tokens() == 0
     # advance by 2