Encoder functions converted to fixed point

[x] Converted apply_MCT_enc and its sub-functions in ivas_mct_enc_mct.c
[x] Removed redundant flags from TCX_ENC_DATA
[x] igf_enc.c functions converted to fixed point

EVS 26.444 BE test passes.
decoder pytests:
MLD scores:
Original inputs: 562 failed, 374 skipped
MLD > 10: 46
MLD > 5 : 108
MLD < 5 : 408
+10dB inputs: 562 failed, 374 skipped
MLD > 10: 168
MLD > 5 : 185
MLD < 5 : 209
-10dB inputs: 562 failed, 374 skipped
MLD > 10: 10
MLD > 5 : 50
MLD < 5 : 502

encoder pytests results:
MLD scores:
Original inputs: 562 tests:
MLD > 10: 17
MLD > 5 : 45
MLD < 5 : 500
+10dB inputs: 562 tests:
MLD > 10: 42
MLD > 5 : 133
MLD < 5 : 387
\-10dB inputs: 562 tests:
MLD > 10: 5
MLD > 5 : 21
MLD < 5 : 536