Add par.set to RemoveConstantFeaturesWrapper()

[pat-s]

fixes #2516

Due to a name clash with popular base learner hyperpars tol, the wrapper hyperpar tol was renamed to wrap.tol and backward comp for tol was added.

library(mlr)
#> Loading required package: ParamHelpers
#> Warning message: 'mlr' is in 'maintenance-only' mode since July 2019.
#> Future development will only happen in 'mlr3'
#> (<https://mlr3.mlr-org.com>). Due to the focus on 'mlr3' there might be
#> uncaught bugs meanwhile in {mlr} - please consider switching.
lrn <- makeLearner("classif.ksvm", C = 123)
lrn <- makeRemoveConstantFeaturesWrapper(lrn, perc = 5)
p <- getHyperPars(lrn)
print(p)
#> $fit
#> [1] FALSE
#> 
#> $C
#> [1] 123
#> 
#> $perc
#> [1] 5
#> 
#> $dont.rm
#> character(0)
#> 
#> $na.ignore
#> [1] FALSE
#> 
#> $wrap.tol
#> [1] 1.490116e-08

^{Created on 2021-02-15 by the reprex package (v1.0.0)}