[6.x] Resolve method templates for polymorphic array callables

[alies-dev]

Fixes #6549.

Passing [Id::class, 'id'] to a callable(int): int parameter used to fail with InvalidArgument when Id::id has its own @template B (@param B $b, @return B), because the method's templates were carried into the callable unresolved and nothing later matched int against B.

When the expected callable is known, CallableTypeComparator::getCallableFromAtomic now infers the method's templates from it: each parameter is bound to the argument type the expected callable passes at that position (a variadic parameter to every remaining argument), and the return type to the expected return type unless that is void. Arguments the expected callable may omit bind to the parameter's default value, with unresolved constant defaults or otherwise uninferred defaults treated as mixed.

Inference only ever makes the callable more specific when that is safe. If a template would land outside its declared bound (for example through class-string), or if any argument, including a default, is not accepted by the resolved parameter type, the templates stay unresolved and the comparison reports the mismatch as before. Tests cover the accepted cases (static, instance, multiple templates, array_map, nested callables, variadics, defaults, void returns) and the rejected ones. The invokable-object branch now uses the same replaceTemplateTypesWithArgTypes helper, which keeps the result typed as TCallable and removes two baseline entries.

[danog]

fix failing CI pls

[alies-dev]

Fixed: the self-analysis failure came from getSingleAtomic() widening the callable to Atomic, it now stays a TCallable. I also tightened the inference so it falls back to the old behaviour whenever resolving the templates could hide a real mismatch (defaults, variadics, template bounds), with tests for each.

[alies-dev]

The version merged here predates the self-analysis fix and the soundness guards for defaults, variadics and template bounds; those are in #12012, which also removes the @psalm-suppress and baseline entries that cover it on 6.x.