tests/micropython: Add test for import from within viper function.

tests/micropython/viper_import.py

@@ -0,0 +1,10 @@
+# test import within viper function
+
+@micropython.viper
+def f():
+    import micropython
+    print(micropython.const(1))
+
+    from micropython import const
+    print(const(2))
+f()

tests/micropython/viper_import.py.exp

@@ -0,0 +1,2 @@
+1
+2