HEADS UP: New default for `ties.method` of {col,row}Ranks()

[HenrikBengtsson]

Background

matrixStats uses ties.method = "max" as the default for colRanks() and rowRanks() for legacy reasons, but we want eventually update to ties.method = "average" to align it with base::rank(), cf. HenrikBengtsson/matrixStats#142.

The process for this migration with be:

1. Give a deprecation warning if ties.method is not explicitly specified (long time; several releases)
2. Give a defunct error if ties.method is not explicitly specified (long time; several releases)
3. Switch the new default to ties.method = "average"

This will have to take a long time in order to make sure end-users out there will notice this and update their code. I hope this will minimize the risk for existing code all of a sudden start producing different results.

Issue

MatrixGenerics gives an ERROR when I revdep check asserting !isTRUE(missing(ties.method)), cf. https://github.com/HenrikBengtsson/matrixStats/blob/feature/default-rank-ties.method/revdep/R_MATRIXSTATS_TIES_METHOD_MISSING%3Ddefunct/problems.md#matrixgenerics