Add the ability to show the size of binary blocks in the output of `AsdfFile.info`

[Cadair]

It would be helpful for me to be able to know if an array in the info output references a binary block and if so know how many bytes are taken on disk by that node (accounting for compression).

[braingram]

There's an open issue for asdftool info to add block information: #1923

I'd have to think about how this would work more generally with AsdfFile.info. Specifically:

• not every AsdfFile comes from a file so the arrays might not have blocks
• deserialization doesn't always preserve the links between objects and blocks (for example astropy Quantity objects require a new array instance so it won't be possible to show blocks corresponding to a Quantity)
• the mapping of object-to-block is many-to-many, would we want to report all blocks for all objects (resulting in multiple reporting of blocks?)

If we add the block header (which contains the used_size) the info output will contain several more entries. We do have options for limiting this output (max_rows) but providing one example here is part of the info output for a L2 roman file currently:

  ├─dq_border_ref_pix_right (NDArrayType)
  │ ├─shape (tuple)
  │ │ ├─[0] (int): 4096
  │ │ └─[1] (int): 4
  │ └─dtype (UInt32DType): uint32
  ├─dq_border_ref_pix_top (NDArrayType)
  │ ├─shape (tuple)
  │ │ ├─[0] (int): 4
  │ │ └─[1] (int): 4096
  │ └─dtype (UInt32DType): uint32
  └─dq_border_ref_pix_bottom (NDArrayType)
    ├─shape (tuple)
    │ ├─[0] (int): 4
    │ └─[1] (int): 4096
    └─dtype (UInt32DType): uint32

and with showing the header:

  ├─dq_border_ref_pix_right (NDArrayType)
  │ ├─shape (tuple)
  │ │ ├─[0] (int): 4096
  │ │ └─[1] (int): 4
  │ ├─dtype (UInt32DType): uint32
  │ └─header (dict)
  │   ├─flags (int): 0
  │   ├─compression (bytes): b'lz4\x00'
  │   ├─allocated_size (int): 278
  │   ├─used_size (int): 278
  │   ├─data_size (int): 65536
  │   └─checksum (bytes): b'MT\xd5a\xbe2L_\x0f\xad.e\xb4!J^'
  ├─dq_border_ref_pix_top (NDArrayType)
  │ ├─shape (tuple)
  │ │ ├─[0] (int): 4
  │ │ └─[1] (int): 4096
  │ ├─dtype (UInt32DType): uint32
  │ └─header (dict)
  │   ├─flags (int): 0
  │   ├─compression (bytes): b'lz4\x00'
  │   ├─allocated_size (int): 278
  │   ├─used_size (int): 278
  │   ├─data_size (int): 65536
  │   └─checksum (bytes): b'MT\xd5a\xbe2L_\x0f\xad.e\xb4!J^'
  └─dq_border_ref_pix_bottom (NDArrayType)
    ├─shape (tuple)
    │ ├─[0] (int): 4
    │ └─[1] (int): 4096
    ├─dtype (UInt32DType): uint32
    └─header (dict)
      ├─flags (int): 0
      ├─compression (bytes): b'lz4\x00'
      ├─allocated_size (int): 278
      ├─used_size (int): 278
      ├─data_size (int): 65536
      └─checksum (bytes): b'MT\xd5a\xbe2L_\x0f\xad.e\xb4!J^'

by changing this line:

asdf/asdf/_core/_converters/ndarray.py

Line 198 in 64eb0eb

return {"shape": obj.shape, "dtype": obj.dtype}

to:

     def to_info(self, obj):
-        return {"shape": obj.shape, "dtype": obj.dtype}
+        info = {"shape": obj.shape, "dtype": obj.dtype}
+        if hasattr(obj, "_data_callback"):
+            info["header"] = obj._data_callback(_attr="header")
+        return info