Create internal links within dd when grid_ggd[:].path is provided

IMAS data model schema has property path in grid_ggd IDS which is a path to another IDS grid_ggd to refer to an existing definition of grid_ggd. For example, radiation.grid_ggd[1].path can refer to edge_profiles.grid_ggd[1] by having value IDS::edge_profiles/grid_ggd(1). This is described in the webpage for OMAS data schema for all different grid_ggd.

This is an important feature for this data model to save space and reduce redundancy. While end users can write their own parser for grid_ggd.path and link to th relevant grid_ggd, it would be a really cool enhacement if IMASDD implements this link internally such that when dd.radiation.grid_ggd[1] is called, it points to dd.edge_profiles.grid_ggd[1] automatically. I envision a check in the constructor call of grid_ggd functions where if path is provided, it creates this link. And an explicit function too, so that one can add the path after creation of IDS object and get this link working.

I don't know though how this will be implemented or if it is even possible in a meaningful way without slowing down IDS access too much since all children grid_ggd are actually separate data types based on parent IDS.

Start with the IMAS data schema page and the grid_ggd constructor entry point described in the issue. Trace how dd.radiation.grid_ggd[1] and dd.edge_profiles.grid_ggd[1] are represented, then assess the proposed constructor-time and explicit post-creation linking behaviors. Done should include a defined path-resolution behavior that preserves practical IDS access without an unspecified performance cost.