Should we create a static factory method for loading VectorValues? [LUCENE-10426]

Similar to the recent work in #11434, it might be useful to add a static factory method for loading `VectorValues` that returns an "empty" `VectorValues` instance if the field doesn't exist in a segment (and also throws if the field is not configured as a vector field). This follows the same pattern of the static factory methods found in `DocValues`}. 

I'm less convinced this is useful to add right now since I don't really see any existing usages of `LeafReader#getVectorValues`}, so maybe the value isn't there right now?

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Migrated from [LUCENE-10426](https://issues.apache.org/jira/browse/LUCENE-10426) by Greg Miller (@gsmiller)

Compare the recent work in #11434 with the static factory methods in DocValues, then inspect usages of LeafReader#getVectorValues. Decide whether a factory for loading VectorValues should provide an empty instance for missing fields and reject non-vector fields; the issue is done when the API need and behavior are resolved.

Written by the indexing model from the issue text.