[Thresholding] Support thresholding with fewer than expected thresholds to match RTL behavior

[SpiritSeeker]

• Updated the Thresholding_rtl class to remove addition of boundary thresholds when number of thresholding is steps is less than (2**out_bits - 1).
• Modified computation of RTL module variables to reflect this.
• Added zero-padding in generated .dat files.
• Removed bias update.

The proposed changes remove the necessity of increasing the bit-width of the thresholds (for unsigned narrow output quantization).

[auphelia]

Thank you @SpiritSeeker !