Move Juno examples into juno_samples

juno_frontend/examples/matmul.jn

-fn matmul<n : usize, m : usize, l : usize>(a : f32[n, m], b : f32[m, l]) -> f32[n, l] {
-  let res : f32[n, l];
-
-  @outer for i = 0 to n {
-    @middle for j = 0 to l {
-      @inner for k = 0 to m {
-        res[i, j] += a[i, k] * b[k, j];
-      }
-    }
-  }
-
-  @exit return res;
-}

juno_frontend/examples/simple3.jn

-fn simple3<n : usize>(a : i32[n], b : i32[n]) -> i32 {
-  let res : i32 = 0;
-
-  @loop
-  for i = 0 to n {
-    res += a[i] * b[i];
-  }
-
-  @exit
-  return res;
-}

juno_scheduler/examples/matmul.sch

-function matmul {
-  partition { @outer, @middle, @inner } on gpu
-  partition @exit on cpu
-
-  parallelize @outer
-  vectorize @inner
-}

juno_scheduler/examples/simple3.sch

-function simple3 {
-  partition @loop on cpu
-  partition @exit on cpu
-
-  vectorize @loop
-}