S3 Vector Store implementation

[MatejNedic]

Before writing docs sadly there is no yet support for S3 Vector Store meaning I can do mock tests only. Is that fine or to skip mock tests completly?

#3834

[MatejNedic]

Hey @ilayaperumalg , before I polish everything fully and write docs. For S3VectorStore class there is no LocalStack implementation yet. Meaning I cannot write integration tests. I can write mock tests tho. So just asking how would Spring team like for me to proceed?

All of the code is done just making it more readable and fixing some imports here and there.