[Compiler FE] Convert dynamic batch to single batch

[jinevening]

What

Let's implement an option to convert a model with a dynamic batch size to a model with a single batch.

For example,

onecc optimize --dynamic_batch_to_single_batch -i dynamic.circle -o single.circle

Why

The option will

1. enable quantization of the model
2. allow the model to be run on backends that do not support dynamic shapes

[seanshpark]

dynamic batch size: where shape of input is like (-1, 224, 244, 3) where -1 is unknown(dynamic) batch size.

[jinevening]

More specifically, shape_signature is like (-1, 224, 224, 3). The below case is possible

shape: (1, 224, 224, 3) shape_signature: (-1, 224, 224, 3)