Generate test application when compose/testcontainers are selected for neo4j

[eddumelendez]

It covers data-neo4j and spring-ai-vectordb-neo4j.

[mhalbritter]

Thanks for the PR! I had to set the password to notverysecret, otherwise the neo4j container would barge at me:

> docker compose up
[+] Running 1/0
 ✔ Container demo-neo4j-1  Created                                                                                                                                                                                                                                                                                 0.0s 
Attaching to neo4j-1
neo4j-1  | Invalid value for password. The minimum password length is 8 characters.
neo4j-1  | If Neo4j fails to start, you can:
neo4j-1  |   1) Use a stronger password.
neo4j-1  |   2) Set configuration dbms.security.auth_minimum_password_length to override the minimum password length requirement.
neo4j-1  |   3) Set environment variable NEO4J_dbms_security_auth__minimum__password__length to override the minimum password length requirement.
neo4j-1  | org.neo4j.commandline.admin.security.exception.InvalidPasswordException: A password must be at least 8 characters.
neo4j-1 exited with code 70