ActivationOperationsConverter

Converter for activation function operations.

This converter implements various activation functions using StableHLO primitives:

• sigmoid: using stablehlo.exponential and arithmetic operations

• softmax: using stablehlo.reduce and stablehlo.broadcast_in_dim

• tanh, gelu, swish: using appropriate StableHLO operations

Note: relu is already implemented in LegacyOperationsConverter

Supports operations as specified in Requirements 2.3:

• Activation functions (relu, sigmoid, softmax)

• Additional activations (tanh, gelu, swish)