Allow conditional function chaining on STRICT_EXPECTED_CALL

Current code might do something like this:

```c
static void setup(int* optional_value)
{
if (optional_value != NULL)
{
STRICT_EXPECTED_CALL(foo(IGNORED_ARG))
.CopyOutArgumentBuffer_result(optional_value, sizeof(optional_value));
}
else
{
STRICT_EXPECTED_CALL(foo(IGNORED_ARG));
}
}
```

Would be nice to reduce that to something like:

```c
static void setup(int* optional_value)
{
STRICT_EXPECTED_CALL(foo(IGNORED_ARG))
.If(optional_value != NULL)
.CopyOutArgumentBuffer_result(optional_value, sizeof(optional_value));
// perhaps needs .EndIf()
}
```

Alternatively, something like this could work:

```c
static void setup(int* optional_value)
{
HELPER_TO_GET_TYPE x = STRICT_EXPECTED_CALL(foo(IGNORED_ARG));
if (optional_value != NULL)
{
x.CopyOutArgumentBuffer_result(optional_value, sizeof(optional_value));
}
}
```

Or maybe:

```c
static void setup(int* optional_value)
{
STRICT_EXPECTED_CALL(foo(IGNORED_ARG)).SaveExpectation(x);
if (optional_value != NULL)
{
x.CopyOutArgumentBuffer_result(optional_value, sizeof(optional_value));
}
}
```

Start by locating the STRICT_EXPECTED_CALL entry point and its existing function-chaining implementation. Compare the proposed conditional chaining and saved-expectation alternatives, then define the supported API and verify that optional copy-out behavior is covered before considering the issue done.

Written by the indexing model from the issue text.