Better CBOR wrappers

[maxtropets]

One more step towards #7542

❗ More of an incremental improvement rather than a finalised version, therefore no fancy docstrings/documentation, etc. It will come once we throw QCBOR away and are fully settled on these wrappers' interface.

Changelist

• Error handling and context business simplified (are they?)
  • look as ugly as before
  • but are more straightforward and avoid duplicating context message, by stacking up getting/parsing flexibly.
• Integer keys comparison changed
  • we allow equality of signed(42) and unsigned(42) now
  • Why? it seems to be the way CBOR libraries treat keys, and is slightly more flexible
  • UPD. Not true anymore, discussed here: Better CBOR wrappers #7549 (comment)
• Some APIs renamed to make more sense
• No \n at the end when to_string()ing
• SimpleValue enum type for commonly used types
• Test coverage (lots of LLM work, thoroughly (sort of) read by me, with lots of human editing sprinkled on top)

✅ Long Test

[Copilot]

Pull request overview

This PR refactors the CBOR wrapper API to simplify error handling and improve usability. The changes remove context parameters from accessor methods in favor of a new rethrow_with_context helper function, allow signed/unsigned integer key equivalence in maps, rename functions for clarity (e.g., parse_value → parse, print_value → to_string), and add comprehensive test coverage.

Key Changes

• Error handling simplified with rethrow_with_context helper that allows flexible context stacking without duplicating messages
• Integer key comparison now treats signed(42) and unsigned(42) as equal in map lookups
• API functions renamed for clarity and consistency (parse, to_string instead of parse_value, print_value)
• Added SimpleValue enum for common CBOR simple values (False, True, Null)
• Added extensive test suite with 70+ test cases covering various CBOR data types

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/crypto/cbor.h	Adds SimpleValue enum, removes context parameters from method signatures, adds rethrow_with_context helper, renames parse_value/print_value to parse/to_string, adds make_bytes helper
src/crypto/cbor.cpp	Removes with_context helper, implements signed_equals_unsigned for map key comparison, adds signed/unsigned cross-conversion in as_signed/as_unsigned, updates to_string to remove trailing newline, improves bytes/simple value printing
src/node/uvm_endorsements.cpp	Updates to use new CBOR API with rethrow_with_context pattern, removes context parameters from accessor calls, changes to use parse instead of parse_value, uses new PARAM_CONTENT_TYPE_HASH_ENVELOPE constant
src/node/cose_common.h	Adds PARAM_CONTENT_TYPE_HASH_ENVELOPE constant (value 259) for COSE hash envelope content type
src/crypto/test/cbor.cpp	New comprehensive test file with 70+ test cases covering integers, strings, bytes, simple values, tags, arrays, maps, and error conditions
CMakeLists.txt	Adds cbor_test unit test target