duplicate module? Term Merge

Mirror issue #978188: duplicate module? Synonym Collapsing

Term merge takes similar terms and combines them into 1 master term & adds the similar term as a synonym of the master term. This is done manually.
Synonym collapsing takes term synonyms (as inputted) and converts them into their master terms. This is done automatically.
Term Merge doesn't keep track of synonyms while Synonym Collapsing does.

They seem to have similar functionality & combining them could provide more valuable use cases.

Term merge would provide the initial manual recognition that terms were synonyms -> thereby combining them & then synonym collapsing would take it from here -> ensuring that duplicate terms do not get created again & terms are synced in real-time.

Having ability to run this 1-time (term merge current functionality), on a schedule or in real-time (Synonym Collapsing) would be great.

Having the ability to choose if synonyms are a...
- 1-time merge (synonyms content merged into master term, but not added as a permanent synonym of master term)
- OR permanent merge (synonyms content merged into master term and synonyms permanently redirected to master term/ permanently added as a synonym of master term) is important.

for example:
1 NEW) if you mis-named a term originally & want to move all content over to a different term BUT not have term become a permanent synonym of (1-time) master term. That way you can keep term separate & ready to receive its own content.
2 CURRENT) if you mistakenly used 2 different terms for the same exact idea & want to permanently combine & redirect all content for these terms. this is current use case for combination of Synonym Collapsing & Term Merge modules.

This could be configured on a vocab or term level basis.