Fix ownership errors in semantic member accessor pullbacks:
- Getter pullbacks: emit copy value operation before storing value.
- Setter pullbacks: track loaded value as a temporary, to be destroyed.
Add tests covering trivial, non-trivial, and address-only properties.
Resolves SR-12778 and SR-12779.
For accessors: make `AbstractFunctionDecl::getDerivativeFunctionConfigurations`
resolve configurations from parent storage declaration `@differentiable`
attributes.
Fixes "no `@differentiable` attribute" non-differentiability error for accessors
whose parent storage declaration `@differentiable` attributes have not been
type-checked (e.g. because the storage declarations are in another file).
Add protocol requirement and class member storage declaration tests.
Resolves TF-1234.
In `AbstractFunctionDecl::getDerivativeFunctionConfigurations`, type-check
`@differentiable` attributes. This is important to populate derivative
configurations for original functions in other files.
Resolves TF-1271.
Exposes TF-1272: fix derivative configurations for cross-file `@derivative`
attributes. This is a more difficult issue.
