[SYCL] Bump native enqueue extension version

In intel#16871 the
`sycl_ext_codeplay_enqueue_native_command` extensions was extended to
add new `interop_handler` APIs for working with SYCL-Graph.

However, the extension macro was not bumped. This is problematic for
users that want to use the extension with graph support, but also
use older oneAPI releases.

```cpp
CGH.ext_codeplay_enqueue_native_command([=](sycl::interop_handle IH) {
    if (IH.ext_codeplay_has_graph() /* is this defined?*/) {
      // Graph path
    } else {
      // Eager path
    }
CGH.host_task(...)
```

By bumping the feature test macro, users can write code that supports
old DPC++ versions.
```cpp
CGH.ext_codeplay_enqueue_native_command([=](sycl::interop_handle IH) {

    if (IH.ext_codeplay_has_graph() /* is this defined?*/) {
      // Graph path
    } else
    {
      // Eager path
    }
CGH.host_task(...)
```

Author: EwanC

sycl/doc/extensions/experimental/sycl_ext_codeplay_enqueue_native_command.asciidoc

@@ -139,8 +139,10 @@ implementation supports.
 |Description
 
 |1
-|The APIs of this experimental extension are not versioned, so the
- feature-test macro always has this value.
+|Initial version defining `handler::ext_codeplay_enqueue_native_command()`.
+
+|2
+|Addition of `interop_handler` methods for `sycl_ext_oneapi_graph` integration.
 |===
 
 === Additions to handler class
@@ -192,6 +194,11 @@ This section defines the interaction with the
 link:../experimental/sycl_ext_oneapi_graph.asciidoc[sycl_ext_oneapi_graph]
 extension.
 
+The APIs defined in this section of the extension specification are only
+available from version 2 of the extension. Usage of the APIs can be guarded in
+user code by checking the value of the <<feature-test-macro,
+feature test macro>>.
+
 The `interopCallable` object will be invoked during `command_graph::finalize()`
 when the backend object for the graph is available to give to the user as a
 handle. The user may then add nodes using native APIs to the backend graph

sycl/source/feature_test.hpp.in

@@ -108,7 +108,7 @@ inline namespace _V1 {
 #define SYCL_EXT_ONEAPI_ENQUEUE_FUNCTIONS 1
 #define SYCL_EXT_ONEAPI_RAW_KERNEL_ARG 1
 #define SYCL_EXT_ONEAPI_PROFILING_TAG 1
-#define SYCL_EXT_ONEAPI_ENQUEUE_NATIVE_COMMAND 1
+#define SYCL_EXT_ONEAPI_ENQUEUE_NATIVE_COMMAND 2
 #define SYCL_EXT_ONEAPI_GET_KERNEL_INFO 1
 #define SYCL_EXT_ONEAPI_WORK_GROUP_MEMORY 1
 #define SYCL_EXT_ONEAPI_WORK_GROUP_SCRATCH_MEMORY 1