Set up H2(in-memory DB) to be used to store templates in cloud env

[arinkulshi-skylight]

This is a optional ticket if we do not have a azure DB.
To address current security concerns with connecting a persistent database to the Spring Boot API, configure an in-memory database to be used temporarily. Ensure to set up such that Azure DB can replace in-mem DB at a future point in time.

• Set up in-memory db H2 in Springboot
• ensure DB initializes with proper schema
• ensure the db aligns with the lifecycle of each user
• test the e2e db lifecycle.