CPU temp occasionally report a very wrong value

[ctacke]

Reading the F7 CPU temp occasionally gives a very high/low temp. We should sanity check this in the managed code if the native code is giving us invalid data.

[doingnz]

I have added the following sanity check in HealthRepoter.cs. Is there a "NaN" value that would be better inplace of hard limits?

    private (string name, Func<object?> function)[] DefaultMetrics =
    {
        new ("health.cpu_temp_celsius", () =>
        {
            var temp = Resolver.Device.PlatformOS.GetCpuTemperature().Celsius;
            return temp < -10 ? -10 : temp > 85 ? 85 : temp;
        }),
        new ("health.memory_used", () => GC.GetTotalMemory(false)),
        new ("health.disk_space_used", () => Resolver.Device.PlatformOS.GetPrimaryDiskSpaceInUse().Bytes),
        new ("info.os_version", () => Resolver.Device.Information.OSVersion),
        new ("up_time", () => Resolver.Services.Get<IReliabilityService>()?.UpTime ?? null),
    };
    ```