LibGfx/ISOBMFF: Add support for jpeg2000 cmap and bpcc boxes

[nico]

This completes support for all jpeg2000 boxes in I.5.3.

cmap demo, for the file attached to #25656, before:

% Build/lagom/bin/isobmff out_71.jpx  
...
  ('cmap')
  [ 16 bytes ]
('jp2c')
- codestream = 2448 bytes

After:

% Build/lagom/bin/isobmff out_71.jpx  
...
  ('cmap')
  - component_index = 0
  - mapping_type = 1
  - palette_component_index = 0
  - component_index = 0
  - mapping_type = 1
  - palette_component_index = 1
  - component_index = 0
  - mapping_type = 1
  - palette_component_index = 2
  - component_index = 0
  - mapping_type = 1
  - palette_component_index = 3
('jp2c')
- codestream = 2448 bytes

I haven't seen the bpcc box in the wild yet, but it's the only missing box type in I.5.3 and it's similar to to a subset of palette box in I.5.3.4, so maybe the implementation is not completely wrong.