nvidia-gpu: add gpu sensor app

The commit adds a dbus sensor app that uses MCTP VDM protocol to read
temperature sensor value from the gpu.

The MCTP VDM protocol is an extension of the OCP specification -
'''
  https://www.opencompute.org/documents/ocp-gpu-accelerator-management-interfaces-v1-pdf
'''

Tested.

Copy the gpusensor app on gb200nvl-obmc machine and run it.
```
root@gb200nvl-obmc:~# ./nvidiagpusensor
```

The app runs without errors.
```
root@gb200nvl-obmc:~# busctl tree xyz.openbmc_project.GpuSensor
└─ /xyz
  └─ /xyz/openbmc_project
    └─ /xyz/openbmc_project/sensors
```

Change-Id: Iee7376a9116489052c690f2e3a1ca8d0f29564dd
Signed-off-by: Harshit Aghera <haghera@nvidia.com>
diff --git a/meson.options b/meson.options
index de8fed4..306a953 100644
--- a/meson.options
+++ b/meson.options
@@ -65,6 +65,12 @@
     description: 'Enable PSU sensor.',
 )
 option(
+    'nvidia-gpu',
+    type: 'feature',
+    value: 'enabled',
+    description: 'Enable GPU sensor.',
+)
+option(
     'external',
     type: 'feature',
     value: 'enabled',