MLBEDSW-3808: Ported search allocator to python

- Straight port of the C++ implementation to python.
- Renamed the allocator from "Search" to "HillClimb"

Change-Id: I50797d541f326d0264daf79bf7866aef32350a60
Signed-off-by: Louis Verhaard <louis.verhaard@arm.com>
diff --git a/ethosu/vela/nn_graph.py b/ethosu/vela/nn_graph.py
index db878bc..c45d0e3 100644
--- a/ethosu/vela/nn_graph.py
+++ b/ethosu/vela/nn_graph.py
@@ -38,7 +38,7 @@
 class TensorAllocator(enum.Enum):
     LinearAlloc = 1
     Greedy = 2
-    Search = 3
+    HillClimb = 3
 
     def __str__(self):
         return self.name