Add import ASV benchmark (#7176)

Author: headtr1ck

asv_bench/benchmarks/import.py

@@ -0,0 +1,18 @@
+class Import:
+    """Benchmark importing xarray"""
+
+    def timeraw_import_xarray(self):
+        return """
+        import xarray
+        """
+
+    def timeraw_import_xarray_plot(self):
+        return """
+        import xarray.plot
+        """
+
+    def timeraw_import_xarray_backends(self):
+        return """
+        from xarray.backends import list_engines
+        list_engines()
+        """