nvidia-gpu: add entity-manager support

The commit add support for reading of the entity-manager configurations
to the gpu dbus sensor app.

Tested.

Build an image for gb200nvl-obmc machine with the following patches
cherry picked. This patches are needed to enable the mctp stack.

https://gerrit.openbmc.org/c/openbmc/openbmc/+/79312
https://gerrit.openbmc.org/c/openbmc/openbmc/+/79422

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

The app is detecting entity-manager configuration on gb200nvl-obmc
machine. The app is also able to detect all the endpoints from the mctp
service dbus tree.

Change-Id: I05a0597964bcc0c135484fed714b6f677adc5891
Signed-off-by: Harshit Aghera <haghera@nvidia.com>
diff --git a/src/nvidia-gpu/meson.build b/src/nvidia-gpu/meson.build
index 4a28491..9918435 100644
--- a/src/nvidia-gpu/meson.build
+++ b/src/nvidia-gpu/meson.build
@@ -1,4 +1,4 @@
-gpusensor_sources = files('NvidiaGpuSensorMain.cpp')
+gpusensor_sources = files('NvidiaGpuSensor.cpp', 'NvidiaGpuSensorMain.cpp')
 
 gpusensor_include_dir = include_directories('.', is_system: true)
 sensor_include_dir = include_directories('../..')