Core encoder and CPE function/sub-functions conversion/integration [allow regression]

[x] core_enc functions converted/integrated: lsf_syn_mem_restore, ProcessIGF_ivas_fx, fb_tbe_enc_ivas_fx, fd_cng_enc, preemph calls in ivas_compute_core_buffer
[x] CPE enc path functions converted/integrated: stereo_classifier, hp_20_fix32, tdm_ol_pitch_comparison, map_input_to_cpe_channels_ivas_fx, stereo_fd_cng_coherence, stereo_td_itd_mdct_stereo, stereo_tca_enc sub-functions