Api: Cache embeddings to avoid recreation of it (Step 3)

[ElSalvo96]

Read before this: #54

We want to cache the embeddings to avoid the new request to OpenApi.
The idea is:

• Create a new table with these fields  
     - Hash of text (unique key) SHA-256 
     - Text
     - Embeddings

• When we save the plugin, we want to split the text with Enter, hash all of that, and search for what sections are not there. 
     - If you found the hash, skip it
     - if you don't find it, call embeddings and save it for the specific hash 

• Connect this new table with the previous embeddings