Remove duplicated code: various functions

• Related issues: #2460 (closed)
• Requested reviewers:

Reason why this change is needed

• Removal of duplicated core-coder functions.

Description of the change

• Removal of duplicated core-coder functions.
• Removes cca 550 lines of source code.
• Add _fx appendix to TonalMDCT function names.

Affected operating points

• All is BE.

Closes #2460 (closed)