move code from Oscar.jl/experimental/GModule/Misc.jl here (#1720)

The idea is to add this code to Nemo.jl,
and then to remove it from Oscar.jl.

Concerning the usefulness of this code (and tests to be added),
I am not sure which vectors shall be supported by the new methods;
vectors of integers are already addressed by other methods.

src/HeckeMiscFiniteField.jl

@@ -222,6 +222,15 @@ function (k::FqPolyRepField)(a::QQFieldElem)
     return k(numerator(a)) // k(denominator(a))
 end
 
+function (k::Nemo.fpField)(a::Vector)
+  @assert length(a) == 1
+  return k(a[1])
+end
+
+function (k::fqPolyRepField)(a::Vector)
+  return k(polynomial(Native.GF(Int(characteristic(k))), a))
+end
+
 
 (F::fqPolyRepField)(a::zzModRingElem) = F(a.data)