R algorithms should not require formula as input

[bartvanb]

Several of the R algorithms currently require a formula as input argument. This needlessly complicates creating tasks for the user, for whom it would be better to provide a list of column names and that the formula is then constructed within the algorithm.

Example:
For the crosstab algorithm I could now provide a function like f="~ site + hospital_id + deadOS" to compute a crosstab grouped by those three columns. I would like instead to provide groupby_cols=['site', 'hospital_id', 'deadOS'] and that the R function is then responsible for creating the function.

Note that the impact of this could be even bigger in the UI, where we will provide column names as a dropdown - the user then only has to select names from a dropdown instead of defining a free text function with column names that they do not know.

Further details:

• This should be done when moving the R algorithms to v4
• Check each algorithm if it uses this
• Fix each algorithm