Fix Mapk extensions

[aballano]

• Added listKOf for ListK as equivalent to List's listOf
  -> With this, there's no need to create normal Lists and Maps to then convert them to the wrapped version via .k(), but instead just create the wrapped versions directly as follows:

val m = mapOf("a" toT  listKOf(1, 2), "b" toT listKOf(3)) // Note that the `toT` will use an Arrow's Tuple to create a MapK
val n = mapOf("a" toT listKOf(4), "c" toT listKOf(5, 6))
val p = m.plus(ListK.semigroup(), n)

• Fix MapK extensions projected over stdlib Map
  -> So now there's no need to convert all maps to MapK because we can use the Map extensions as follows (note that we cannot still use List.semigroup tho):

val m = mapOf("a" to 1, "b" to 3)
val n = mapOf("a" to 5, "c" to 5)
val p = m.plus(Int.semigroup(), n)

Fixes #140

[pakoito]

ez pz

[aballano]

@raulraja Hope this is ok tho 😅