feat: database setup

[elianiva]

since most forms would be unstructured, it would be better to use schemaless nosql database such as mongodb
although i'm not sure if we really need an ORM, probably not since the official mongodb driver would suffice

even though the database is schemaless, at least we need to set the schema for these things:

• user schema
• base form schema (each form will consists of blocks, in which each block will have their own schema, and a single form will consists of multiple schema, hence we need the schemaless db since each form will have different combination of schema)