Cache and extend AttributeError member-name suggestions (static members and enum values)

[jhonabreul]

What does this implement/fix? Explain your changes.

Two related changes to the AttributeError "Did you mean ...?" suggestions (added in #124 / #129):

1. Cache the suggestions (performance fix).
Building the hint reflects over the managed type's entire member set (GetMembers with FlattenHierarchy), snake_cases every member, and runs a Levenshtein scan. This ran on every miss with no caching — and getattr(obj, name, default) / hasattr trigger it too, because the work happens on the miss path before CPython suppresses the error. A workload that probes the same missing names repeatedly — e.g. a per-bar getattr(self, "_optional", None) on a .NET-derived object — pays the full O(members) reflection + ranking cost on every call.

Two caches in ClassBase fix this:

• _candidateNameCache (Type -> HashSet<string>): the deduplicated snake_case member names, computed once per type.
• _suggestionCache ((Type, name) -> string): the fully-built " Did you mean: ...?" hint (empty when there is nothing to suggest), memoized per (type, missing-name).

A repeated miss is now a single dictionary lookup. Suggestions and message text are unchanged by this part.

Measured on a real Lean multi-symbol minute backtest (a Python QCAlgorithm subclass doing many per-bar optional-attribute probes), profiled with dotnet-trace: the suggestion path (GetAttrHook -> reflection + LevenshteinDistance + ToSnakeCase) accounted for ~93% of OnData CPU. With the cache the same backtest goes from not finishing (aborted, >15× slower) to ~93s, on par with the last build without the suggestion feature (~90s), with identical results.

2. Extend suggestions to type-object misses (static members and enum values).
A missing attribute on a reflected type object — a mistyped static member or enum value such as DayOfWeek.Sundey — previously raised the bare CPython type object 'X' has no attribute 'Y' with no hint, because the miss hook was installed on reflected types (which govern their instances), whereas type-object access is governed by the CLR metatype.

This installs the same miss-only __getattr__ hook on the CLR metatype (allowing the redirect when tp_getattro is type_getattro, not only the generic getattr), so a type-object miss is enriched the same way instance misses are. It stays miss-only, so hits, submodule imports and hasattr on type objects are unaffected. BuildMissingAttributeMessage resolves the target from either a CLRObject (instance) or a ClassBase (type object) and uses CPython's type object 'T' wording for the latter.

Suggestions reuse the existing ranking and the snake_case convention Python exposes members under (ToSnakeCaseMemberName): methods become lower_snake, while enum values, consts and static-readonly members become UPPER_SNAKE. Examples of the new messages:

DayOfWeek.Sundey  -> type object 'DayOfWeek' has no attribute 'Sundey' Did you mean: 'SUNDAY'?
Math.PII          -> type object 'Math' has no attribute 'PII' Did you mean: 'PI', 'min', 'pow', 'sin'?
String.Empy       -> type object 'String' has no attribute 'Empy' Did you mean: 'EMPTY', 'copy'?
Math.Sqrtt        -> type object 'Math' has no attribute 'Sqrtt' Did you mean: 'sqrt'?

Every suggested name resolves (DayOfWeek.SUNDAY, String.EMPTY, Math.sqrt, ...). Instance-attribute suggestions are unchanged (obj.lenght -> 'length').

Does this close any currently open issues?

No pythonnet issue is open. Part 1 fixes the backtest performance regression introduced with the AttributeError suggestion feature (#124 / #129); part 2 extends that feature to static/enum members.

Any other comments?

Part 1 is behavior-preserving (identical messages). Part 2 only changes the previously unhinted type-object miss path, adding suggestions and matching CPython's type object 'T' wording.

Bumps the package version to 2.0.58 (<Version>, AssemblyVersion/AssemblyFileVersion and the perf-test baseline reference).

Checklist

• Make sure to include one or more tests for your change
• If an enhancement PR, please create docs and at best an example
• Ensure you have signed the .NET Foundation CLA
• Add yourself to AUTHORS
• Updated the CHANGELOG