adding a tensor adaptor to collect node indices from geometries

[RiccardoRossi]

📝 Description
this is a tensor adaptor which collects the node ids from geometries.

🆕 Changelog

[rubenzorrilla]

I'd suggest naming it GeometryIdTensorAdaptor. I think IndexTensorAdaptor is not very self-descriptive.

[matekelemen]

Ok, after looking at the tests and reading the PR's title, I understand what yoou're doing, but the class' name is unbelievably misleading.

To me, it was clear as day that GeometryIdsTensorAdaptor fetches the IDs of geometries. But no, it fetches the node IDs of each geometry. Please rename it to something more intuitive.

[RiccardoRossi]

Ok, after looking at the tests and reading the PR's title, I understand what yoou're doing, but the class' name is unbelievably misleading.

To me, it was clear as day that GeometryIdsTensorAdaptor fetches the IDs of geometries. But no, it fetches the node IDs of each geometry. Please rename it to something more intuitive.

ConnectivityIdsTrnsorAdaptor?

I don t mind changing the name but i am out of ideas...suggestions are welcomd

On my side,
I am worried about

1. what the copy constructor should do
2. should we allow changing the ids? I woukd say no, otherwise we need to also pass the modelpart nodes in the constructot

[sunethwarna]

I am ok with this, with the minor concerns...

[RiccardoRossi]

@sunethwarna in principle it is ready (with your suggestions and a renamed name)

[sunethwarna]

Thanks @RiccardoRossi :)