tests: Split out float test from builtin_round.py.

tests/basics/builtin_round.py

-# test round()
+# test round() with integral values
 
-# check basic cases
 tests = [
     False, True,
     0, 1, -1, 10,
-    0.0, 1.0, 0.1, -0.1, 123.4, 123.6, -123.4, -123.6
 ]
 for t in tests:
     print(round(t))
-
-# check .5 cases
-for i in range(11):
-    print(round((i - 5) / 2))

tests/float/builtin_float_round.py

+# test round() with floats
+
+# check basic cases
+tests = [
+    0.0, 1.0, 0.1, -0.1, 123.4, 123.6, -123.4, -123.6
+]
+for t in tests:
+    print(round(t))
+
+# check .5 cases
+for i in range(11):
+    print(round((i - 5) / 2))