add support for Operators for Generic target needed in MAGIA (again)

[marchioa]

This PR is a PR193 follow up that adds the support for Operators needed for MAGIA that are not available in the Generic target.

Added

• Elu: fp32 only
• LeakyRelu: fp32 only
• Selu: fp32 only
• Scatter (deprecated) and ScatterElements: s8, u8, and fp32. Easily extendible to other standard datatypes as it is implemented with a define-based template.
• Col2Im: s8, u8, and fp32. Exactly as in ScatterElements, it is implemented with a define-based template supporting any standard datatype.
• Resize: s8, u8, and fp32. Easily extendible to other standard datatypes not because of a define-based template but because implemented with void pointers and simple helper functions depending on the data type.
• ConvTranspose: fp32 only.
  • adds the 2D version of the kernel (only 1D was available).
  • adds support for missing optional attributes.
  • adds 1D and 2D tests.
  • general refactor (Parser, Layer, and Template). Main change: moved most parsing to the general ConvTranspose parser, leaving the dimension specific parser much simpler.

Changed

• DeeployTypes.py: I added the possibility for an onnx operator to have empty inputs (e.g., Resize). I simply added some guards in the input parsing, buffer allocation and initialization, etc. to skip those inputs that have no name or type.

Fixed

• ConvTranspose. Solved issue with output buffer shape due to shape computation in ConvTransposeLayer.
  • TODO: check it with @callme-sam before making PR ready-for-review

PR Merge Checklist

1. The PR is rebased on the latest devel commit and pointing to devel.
2. Your PR reviewed and approved.
3. All checks are passing.
4. The CHANGELOG.md file has been updated.
5. If the docker was modified, change back its link after review.

[Victor-Jung]

@marchioa