…8639)

The PoC's TestClassModelBuilder built its fully-qualified type names with SymbolDisplayMiscellaneousOptions.IncludeNullableReferenceTypeModifier, then fed the resulting FQN into both casts (where '?' is harmless and merely cosmetic, since the emitted setter already uses 'value!') and 'typeof(...)' expressions (where '?' on a reference type is invalid C# and produces CS8639).

Removing the flag fixes 'typeof(string?)' / 'typeof(MyRef?)' while preserving 'typeof(int?)' (nullable value types are rendered via UseSpecialTypes, which is unaffected).

Adds a focused regression test that runs the Roslyn compiler over the generated source and asserts both the textual shape ('typeof(global::Sample.TestContext)', 'typeof(string)', 'typeof(int?)') and the absence of any compile errors.

Discovered while building tests for microsoft#8574; depends on microsoft#9004 for the test infrastructure.

Part of microsoft#1837.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Today TestClassModelBuilder only enumerates members directly declared on the
`[TestClass]` type. As soon as a fixture extends a base class, MSTest members
(`[TestInitialize]`, `[TestCleanup]`, `[TestMethod]`, the `[TestContext]`
property, ...) declared on the base disappear from the generated registry.

This change makes the builder walk the inheritance chain (stopping at
`System.Object`):

* Methods and properties are folded from base types into the model.
* Iteration is derived-first; an override or `new`-shadowed member with the
  same signature/name wins over the base declaration. The signature key
  includes ref-kinds so genuine overloads survive.
* Attributes are collected across the `OverriddenMethod` / `OverriddenProperty`
  chain (deduped by attribute class FQN) so an `override` that does not
  re-apply `[TestMethod]` still sees the base attribute - matching the
  runtime `GetCustomAttributes(inherit: true)` semantics.
* Accessibility is broadened to include `Protected` / `ProtectedOrInternal` /
  `ProtectedAndInternal` so abstract bases can expose their hooks to the
  emitted code (which lives in the consumer's assembly).
* Constructors are NEVER inherited (only taken from the leaf type).

Adds 9 new tests covering: inherited methods, multi-level inheritance,
overridden virtual (attribute inheritance + de-dup), `new`-hidden methods,
overload preservation, inherited properties, no inherited constructors,
abstract-base fold-down, and not walking past `System.Object`.

Part of microsoft#1837. Depends on microsoft#9004 (test project), microsoft#9005 (typeof nullable).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Adds an AssemblyAttributes property to the emitted MSTestReflectionMetadata registry containing all attributes declared with [assembly: ...] in the same compilation. The attribute payload is built via the existing AttributeApplicationModel pipeline (reused from class/method attribute emission), so adapters can iterate without calling Assembly.GetCustomAttributes at runtime.

Part of microsoft#1837. Stacked on microsoft#9004, microsoft#9005, microsoft#9006.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>