This function scans a vector of semicolon-delimited target strings (`curve_quant`) and identifies which entries contain missing targets, indicated by the presence of `"<sample_matrix>-NA"` for each target listed in `sample_matrices`.
calcSampleTargetNAs(curve_quant, sample_matrices)A two-column matrix where each row gives the (row, col) index of a match: - `row`: the index in `curve_quant` - `col`: the index in `sample_matrices` where a corresponding `"-NA"` entry was found. If no matches are found, returns an empty matrix with 0 rows and 2 columns.