[1.4.x] Aliasing of phrases/words

[spaceemotion]

(as per #764 (comment))

Some search queries are similar in semantics, but similar in the wording. When users look for discount codes, things like "sale" and "black friday" could be helpful to have a page rank higher for people - especially around those parts of the year. This makes for a better experience for the user as they'll likely not try 5 different wordings right away.

Other examples/aliases:

1. purchase -> order, transaction
2. export -> download
3. refund -> money back, i was charged

I know that a semantic search that uses embeddings will very likely catch these things, but I do see that outside of the scope of aliasing, and thus an additional feature down the line.