Quartus Merge layers

[bo3z]

A# Description

📝 Merge, Concatenate and Dot layers for the Quartus backend

• Extend support in io_stream to allow multiple inputs per model
• Add support for Merge (Add, Subtract, Multiply, Average, Minimum, Maximum) layers in Quartus backend
• Add support for Dot layers in Quartus backend
• Add support for Concatenate (1D, 2D and 3D) layers in Quartus backend

Type of change

• New feature (non-breaking change which adds functionality)

Tests

• Expanded existing PyTest to include the Quartus backend under pytest/test_merge.py
• HLS Synnthesis to verify correct synthesis, resource usage and layers.

Checklist

• I have read the guidelines for contributing.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.