Add Relude.Extra.Tuple module with useful utilities

[chshersh]

The following functions might be useful sometimes:

dupe    :: a -> (a, a)
fstWith :: (a -> b) -> a -> (a, b)
sndWith :: (a -> b) -> a -> (b, a)
mapBoth :: (a -> b) -> (a, a) -> (b, b)

[cronokirby]

Instead of fstWith and sndWith maybe mapSnd and mapFst where they denote where the mapped value goes. These names also coincide better with mapBoth

[chshersh]

I don't like mapSnd and mapFst names because for these functions I expect types to be:

mapFst :: (a -> b) -> (a, c) -> (b, c)
mapSnd :: (a -> b) -> (c, a) -> (c, b)

The idea is to return the element itself with the result of the mapped value.