IVGCVSW-4007 Add StandInLayer for unsupported operations in TfLiteParser

* Fixed bug in custom operator support that caused all custom operators
  to be parsed as a DetectionPostProcessLayer
* Added support for handling unsupported operators (built-in or custom)
  by replacing them with a StandInLayer in the generated network
* Added options to TfLiteParser to control whether we want to use
  StandInLayers when we encounter unsupported operators, or we prefer
  to throw a ParserException as until now

Signed-off-by: Aron Virginas-Tar <Aron.Virginas-Tar@arm.com>
Change-Id: I125a63016c7c510b1fdde6033842db4f276718c4
diff --git a/CMakeLists.txt b/CMakeLists.txt
index e3b1f8f..b451d9c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -711,6 +711,7 @@
              src/armnnTfLiteParser/test/TransposeConv.cpp
              src/armnnTfLiteParser/test/Transpose.cpp
              src/armnnTfLiteParser/test/Unpack.cpp
+             src/armnnTfLiteParser/test/Unsupported.cpp
              src/armnnTfLiteParser/test/LoadModel.cpp
              src/armnnTfLiteParser/test/GetBuffer.cpp
              src/armnnTfLiteParser/test/OutputShapeOfSqueeze.cpp