Remove rom_com files duplications and unused ROM tables and fft_rel()

Closes #1961

Merge of duplicated files:

• ivas_rom_com.c and ivas_rom_com_fx.c
• ivas_rom_com.h and ivas_rom_com_fx.h
• rom_com.c and rom_com_fx.c
• rom_com.h and rom_com_fx.h
• tools.c and tools_fx.c
• igf_enc.c and igf_enc_fx.h

Removal of unused ROM tables and one unused function:

• table sincos_t_ext[] and function fft_rel()
• tables dirac_gains_norm_term_int[], dirac_gains_norm_term_fx[], dirac_gains_Pnm_int[][], dirac_gains_trg_term_int[][]

Others:

• rename file ivas_rotation_com.c to ivas_rotation_com_fx.c
• formatting around places affected by the changes above