TinyViT on non-tiled Siracusa

[diaconuccalin]

This PR brings the changes required for a working minimal TinyViT on the Siracusa platform, without tiling.

Added

• PULP 2D FP DW conv Im2Col template and kernel, with bias support.
• Bias support for PULP 2D FP regular conv Im2Col in template & kernel.
• PULP FP DW conv 2D parser.
• FP conv 2D (simple & DW), reshape & skip connection, and TinyViT demo tests to the non-tiled Siracusa CI pipeline.
• FP bindings and mappings for PULP slice, DW conv 2D, and reduce mean operations.
• FP PULP DW conv lowering optimization pass similar to the existent one for integer version.
• RemoveEmptyConvBiasPass to the PULP optimizer.
• PULPClusterEngine now accepts a n_cores parameter to set the number of cores used
• annotateNCores method to PULPDeployer that adds an n_cores key to all PULPClusterEngine templates' operatorRepresentations

Changed

• Reduced size of reshape & skip connection test, for non-tiled Siracusa memory compatibility.
• changed _mapNode to _selectEngine which reduces the responsibility of that function to, as the name states, just engine selection

Fixed

• Fixed bug for non-batched elements in the PULPOpen FP GEMM and matmul templates.
• Added underscore to the beginning of closure names to avoid naming issues when they start with unsupported first characters (like numbers).
• Data types in the PULPOpen FP add and mul templates.

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