dawn.json: Expose the driver version in the adapter.

And use it to print the driver version at the start of
dawn_end2end_tests. This will help when figuring out issues
happening on CQ but not necessarily locally.

Bug: None

Change-Id: Ibdb9ab8cab53cc1e1cf8a807da53edeca616bed9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/29602
Reviewed-by: Stephen White <senorblanco@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>

src/dawn_native/opengl/BackendGL.cpp

@@ -170,6 +170,9 @@ namespace dawn_native { namespace opengl {
             const char* vendor = reinterpret_cast<const char*>(mFunctions.GetString(GL_VENDOR));
             mPCIInfo.vendorId = GetVendorIdFromVendors(vendor);
 
+            mDriverDescription = std::string("OpenGL version ") +
+                                 reinterpret_cast<const char*>(mFunctions.GetString(GL_VERSION));
+
             InitializeSupportedExtensions();
 
             return {};