Create `opt_check_tbl_col_horizon_timediff` function

[annakrystalli]

This function is a variation on https://github.com/Infectious-Disease-Modeling-Hubs/hubValidations/blob/main/R/cfg_check_tbl_col_timediff.R

Differences:

• rather than looking for a single time difference between values of columns in each row, it can vary row by row.
• time diff is determined by the value in a horizon column.