Simplify index synonyms syntax

[arkid15r]

Is your feature request related to a problem? Please describe.
We have synonyms supports and currently they are in JSON format (ready to be consumed by Algolia index)

Describe the solution you'd like
Simplify file structure to support following (on issue synonyms example issues.json -> issues.txt:

mern: express, javascript, mongo, node, react, typescript // for one-way synonyms
js, javascript // regular synonyms

Update IndexBase::reindex_synonyms to efficiently parse .txt files with simplified structure and create synonyms structure for index.save_synonyms(synonyms, {"replaceExistingSynonyms": True})

[nitinawari]

Can i work on this ?

[nitinawari]

@arkid15r should i completely remove json reading or it must stay for backup
here is code sample
# Try reading .txt file first, fall back to .json if not found
file_paths = [
f"{settings.BASE_DIR}/apps/{app_name}/index/synonyms/{index_name}.txt",
f"{settings.BASE_DIR}/apps/{app_name}/index/synonyms/{index_name}.json"
]

[arkid15r]

We'll use .txt files only.