feat: updates for cbor all the things

[robinbryce]

• remove use of /tmp in favour of current working directory. tmp breaks the examples for macos
• note that indexing and retrieval for the meta map is a future release thing.
• describe how to capture the leaf hash from registration so verification can be accomplished directly
• purposefuly don't get into the details of computing the leaf hash
• remove use of ${SCRIPTS} in favour of python -m which works on all platforms

[JAG-UK]

Minor nits, have a look

[robinbryce]

This can merge monday 16th but not before

[SteveLasker]

Putting a temp block untill backend changes merge, confirming the docs work with production.

python3 -m datatrails_scitt_samples.scripts.register_signed_statement   --signed-statement-file $SIGNED_STATEMENT_FILE   --output-file $TRANSPARENT_STATEMENT_FILE   --log-level INFO
INFO:register-statement:submit_statement: signed-statement.cbor
Traceback (most recent call last):
  File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/home/steve/demos/scitt-demos/datatrails-scitt-samples/datatrails_scitt_samples/scripts/register_signed_statement.py", line 154, in <module>
    main()
  File "/home/steve/demos/scitt-demos/datatrails-scitt-samples/datatrails_scitt_samples/scripts/register_signed_statement.py", line 104, in main
    op_id = submit_statement_from_file(ctx, args.signed_statement_file)
  File "/home/steve/demos/scitt-demos/datatrails-scitt-samples/datatrails_scitt_samples/statement_registration.py", line 65, in submit_statement_from_file
    return submit_statement(ctx, data_file.read())
  File "/home/steve/demos/scitt-demos/datatrails-scitt-samples/datatrails_scitt_samples/statement_registration.py", line 46, in submit_statement
    msg = decode_cbor_data(response.content)
  File "/home/steve/demos/scitt-demos/datatrails-scitt-samples/datatrails_scitt_samples/statement_registration.py", line 20, in decode_cbor_data
    return cbor2.loads(data)
_cbor2.CBORDecodeEOF: premature end of stream (expected to read 65536 bytes, got 116 instead)

[SteveLasker]

@robinbryce, can you please verify: a67cc43