Since creating the vector index does not lead to creation
of a view table [#24438] (whose version info had been logged in
`system_schema.scylla_tables`) we lack the information about
the version of the index.
The mentioned version is used to recognize the quick-drop-create
index with the same parameters that needs to be rebuild.
The case is mainly experienced while testing, benchmarking
or experimenting with Vector Search.
Nevertheless it is important to have it considered, as it is really
weird having seen that DROP and CREATE commands did not change
anything.
Although being nice "optimization" to use the same old index,
the rebuild feels more natural for the get-to-know-VS-users.
Should not change anything in a real production environment.
The solution we arrived at is to add the version as a field in
options column of `system_schema.indexes`.
The version of vector index is a base table's schema version
on which the index was created.
The table's schema version changes everytime a table is changed
meaning that CREATE INDEX or DROP INDEX statement also change it.
Every index has a different index version, so it allows to identify
them easily.
This patch implements the solution described above.
909a51e524