Functions in ivas_ism_metadata_enc.c 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: 13
MLD > 5 : 47
MLD < 5 : 502

encoder pytests results:
MLD scores:
Original inputs: 562 tests: 90 passes, 472 failures, 374 skipped
MLD > 10: 16
MLD > 5 : 24
MLD < 5 : 520
+10dB inputs: 562 tests: 90 passes, 472 failures, 374 skipped
MLD > 10: 26
MLD > 5 : 92
MLD < 5 : 444
\-10dB inputs: 562 tests: 76 passes, 486 failures, 374 skipped
MLD > 10: 5
MLD > 5 : 19
MLD < 5 : 538