Few functions in ivas_decision_matrix_dec, lsf_tools converted to fixed.

Functions create_IDCT_N_Matrix, ivas_dirac_dec_get_frequency_axis, ivas_decision_matrix_dec converted to fixed or updated with BASOPs.

Pytests: 573 failed, 381 skipped and 1 passed for original inputs, +10dB scaled and -10dB scaled inputs.

MLD:
Original: 7 cases > 5
8.623271 9.196089 9.304973 10.832478 10.853292 12.952374 22.458605

+10dB: 21 cases > 5
5.371162 5.505808 5.577011 5.663041 5.663041 6.287786 6.327793 6.992575 7.858168 10.755767 10.755767 11.334802 14.898525 16.603626 16.975687 19.353098 19.374039 19.761044 23.581322 27.03828 38.923706

-10dB: 5 cases > 5
5.965 6.009636 8.7374 15.85026 24.995966