Add the tests I forgot!

Test plan: `make check`

Auditors: csilvers

Author: benjaminjkraft

testdata/symbol_alias_none_in.py

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+from foo import some_function
+
+
+def do_thing():
+    some_function(1)

testdata/symbol_alias_none_out.py

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+import bar
+
+
+def do_thing():
+    bar.new_name(1)

testdata/symbol_in.py

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+from foo import some_function
+
+
+def do_thing():
+    some_function(1)

testdata/symbol_out.py

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+from bar import new_name
+
+
+def do_thing():
+    new_name(1)