New InceptionV3 module, Benchmark models modules and main.py unit tests and code restructure

[YaredTaddese]

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Benchmark Models change

• Write InceptionV3 module for training
• Restructure training code to be reusable for all model architecture implementation modules
• Restructure and modify VGG module for training and unit testing
• Restructure Resnet module for unit testing
• Write unit tests for all above benchmark models and training code

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main.py change

• Restructure main.py code for reusability and unit testing
• Write unit tests for main.py