added interface base name calculation

test/test_classifier_utilities.py

+import pytest
+from inventory_provider.routes import classifier
+
+@pytest.mark.parametrize('interface_name,base_name', [
+    ('ae0', 'ae0'),
+    ('ae0.0', 'ae0'),
+    ('ae1.0', 'ae1'),
+    ('ae10.2603', 'ae10'),
+    ('et-3/1/2', 'et-3/1/2'),
+    ('et-3/1/2.100', 'et-3/1/2'),
+    ('xe-2/1/0', 'xe-2/1/0'),
+    ('xe-2/1/0.933', 'xe-2/1/0'),
+
+    # degenerate cases ... check expected regex behavior
+    ('xe-2/1/0.933.933', 'xe-2/1/0.933'),
+    (' sss.333.aaa ', ' sss.333.aaa '),
+    (' sss.333.aaa .999', ' sss.333.aaa ')
+]
+)
+def test_base_interface_name(interface_name, base_name):
+    assert classifier.base_interface_name(interface_name) == base_name