add docstrings and complete function signatures to synchronous api, and tests for the above

Author: d-v-b

src/zarr/api/asynchronous.py

@@ -765,9 +765,9 @@ async def open_group(
 
 
 async def create(
-    shape: ChunkCoords,
+    shape: ChunkCoords | int,
     *,  # Note: this is a change from v2
-    chunks: ChunkCoords | None = None,  # TODO: v2 allowed chunks=True
+    chunks: ChunkCoords | int | None = None,  # TODO: v2 allowed chunks=True
     dtype: npt.DTypeLike | None = None,
     compressor: dict[str, JSON] | None = None,  # TODO: default and type change
     fill_value: Any | None = 0,  # TODO: need type
@@ -789,7 +789,7 @@ async def create(
     meta_array: Any | None = None,  # TODO: need type
     attributes: dict[str, JSON] | None = None,
     # v3 only
-    chunk_shape: ChunkCoords | None = None,
+    chunk_shape: tuple[int, ...] | int | None = None,
     chunk_key_encoding: (
         ChunkKeyEncoding
         | tuple[Literal["default"], Literal[".", "/"]]