[Store][PG] Allow to change vector type and index type

[lyrixx]

Q	A
Bug fix?	no
New feature?	yes
Docs?	no
Issues
License	MIT

Gemini gives me vector of 3072 dimms.
But PG vector can't handle that much dimms. ref
So a workarround is to change the vectory type, and so the index.

Example:

app=# \d gemini
                   Table "public.gemini"
  Column   |     Type      | Collation | Nullable | Default 
-----------+---------------+-----------+----------+---------
 id        | uuid          |           | not null | 
 metadata  | jsonb         |           |          | 
 embedding | halfvec(3072) |           | not null | 
Indexes:
    "gemini_pkey" PRIMARY KEY, btree (id)
    "gemini_embedding_idx" hnsw (embedding halfvec_cosine_ops)

app=# select count(*) from gemini ;
 count 
-------
   384
(1 row)

[chr-hertel]

Thank you @lyrixx.