Add function to create table of sample compound idx

[annakrystalli]

This functions will basically just call expand_model_out_val_grid(include_sample_ids = TRUE) subsetting just for sample output types (see hubverse-org/hubValidations#98 ) but will rename the outout_type_id column to compound_idx.

Such a function is for demo purposes, to help folks, in conjunction with the sample output type documentation page to understand how the compound task id set informs the structure of samples within their own hub.

[annakrystalli]

The function should also have a coumpound_taskid_set argument that allows user to override the round coumpound_taskid_set with a coarser set (but not a finer set).

This can then be used to validate coarser coumpound_taskid_sets in https://github.com/hubverse-org/hubValidations/issues/88

I also feel this function should move to hubValidations