Integrate lib_com functions in lib_enc modules

[x] Integrated all the functions present in ivas_stereo_dft_com.c, ivas_stereo_mdct_bands_com.c, delay_comp.c and ivas_stereo_mdct_stereo_com.c
[x] Integrated functions invdct4_transform, ivas_get_df_ratio_bits, ivas_qmetadata_azimuth_elevation_to_direction_vector, masa_sq, only_reduce_bits_direction in encoder
[x] ivas_qmetadata_direction_vector_to_azimuth_elevation is integrated but disabled due to the high deviations observed after integrating the function.