Further resolve already supported types

[tuckermcclure]

Summary

Make PortableStructs.from_dict more robust for generic tuples, dictionaries, tagged values, and structs without keyword constructors.

Motivation

Some parsed YAML/JSON values arrive with only partial type information from the containing field, such as Tuple, NamedTuple, AbstractDict, or Dict. The previous generic loading paths either skipped recursive decoding in some cases, treated dictionary type tags inconsistently, or relied too heavily on keyword constructors.

Changes

• Add recursive loading support for bare Tuple and generic NamedTuple.
• Validate tuple lengths instead of silently truncating through zip.
• Strip type_key entries before redispatching tagged dictionaries.
• Preserve requested-type validation after resolving type tags.
• Add explicit dictionary loading paths for:
  • Dict
  • Dict{K,V}
  • OrderedDict
  • OrderedDict{K,V}
  • AbstractDict
  • AbstractDict{K,V} via OrderedDict
• Avoid guessing concrete implementations for arbitrary abstract dictionary subtypes.
• Add dict-backed loading for Rational and Complex.
• Add a narrow positional-constructor fallback for concrete structs whose dict keys exactly match field names.
• Update README constructor guidance to mention both keyword and positional construction.
• Remove a misleading type tag from the roses fixture so it remains ordinary dictionary data.

Tests

Added coverage for:

• generic tuple loading and tuple length mismatch
• generic named tuple loading with type_key filtering
• positional construction from exact field-name mappings
• abstract and concrete dictionary loading behavior
• rejection of arbitrary abstract dictionary subtypes
• tagged value resolution and requested-type validation
• dict-backed Rational and Complex loading

I manually tested that this works with some demanding downstream projects as well.