fix: Start laying out the sequence structure

https://docs.qblox.com/en/main/cluster/q1_sequence_processor.html#sequences

src/qibolab/_core/instruments/qblox/sequence.py

@@ -0,0 +1,29 @@
+from typing import Annotated
+
+from pydantic import PlainSerializer, PlainValidator
+
+from qibolab._core.serialize import Model
+
+from .ast_ import Program
+from .parse import parse
+
+
+class Waveforms(Model):
+    pass
+
+
+class Weights(Model):
+    pass
+
+
+class Acquisitions(Model):
+    pass
+
+
+class Sequence(Model):
+    waveforms: Waveforms
+    weights: Weights
+    acquisitions: Acquisitions
+    program: Annotated[
+        Program, PlainSerializer(lambda p: p.asm()), PlainValidator(parse)
+    ]