Add missing infrastructure tests

[EmilHvitfeldt]

bake method errors when needed non-standard role columns are missing

c(
"tests/testthat/test-combine_stringdist.R", 
"tests/testthat/test-date_after.R",                              
"tests/testthat/test-date_before.R", 
"tests/testthat/test-date_nearest.R", 
"tests/testthat/test-difftime.R", 
"tests/testthat/test-encoding_binary.R", 
"tests/testthat/test-encoding_frequency.R", 
"tests/testthat/test-maxabs.R", 
"tests/testthat/test-minmax.R", 
"tests/testthat/test-robust.R", 
"tests/testthat/test-time_event.R", 
"tests/testthat/test-unit_normalize.R", 
"tests/testthat/test-yeet.R"                 
)

empty printing

c(
"tests/testthat/test-combine_stringdist.R", 
"tests/testthat/test-encoding_binary.R",                         
"tests/testthat/test-encoding_frequency.R", 
"tests/testthat/test-yeet.R"
)

empty selection prep/bake is a no-op

c(
"tests/testthat/test-combine_stringdist.R", 
"tests/testthat/test-encoding_binary.R",                         
"tests/testthat/test-encoding_frequency.R", 
"tests/testthat/test-yeet.R"
)

empty selection tidy method works

c(
"tests/testthat/test-combine_stringdist.R", 
"tests/testthat/test-encoding_binary.R",                         
"tests/testthat/test-encoding_frequency.R", 
"tests/testthat/test-yeet.R"
)

printing

c(
"tests/testthat/test-encoding_binary.R", 
"tests/testthat/test-encoding_frequency.R"                          
)