Initial release of the BlockwiseParallelTransformerAttention class.
Implemented the forward pass of the module, which splits the input sequence into blocks and computes the attention output for each block in parallel.
Added support for variable-length input sequences by padding the input sequence to the maximum sequence length.
Added support for multi-head attention by computing the attention output for each head separately and concatenating the results.
Added a feedforward module after the attention module to apply a nonlinearity to the output.
Tested the module on a small dataset and verified that it produces the expected output.