Add CLI command to show current schema(s)

[islamaliev]

Is the request related to a problem?

It might be hard for a user who is not familiar with the database structure to get started and make changes.
At the moment it's not possible to read the current schema for any collection in the database using CLI.
Introspection queries are tedious to write and the result is not very consice.

The feature you would like

Would be nice to be able to write defradb client schema show that would output schemas for all collections:

type Author {
    name: String
    age: Int
    verified: Boolean
    favouritePageNumbers: [Int!]
    book: [Book]
}

type Book {
    name: String
    rating: Float
    author: Author
    publisher: Publisher
}

type Publisher {
    name: String
    address: String
    yearOpened: Int
    book: Book @primary
}

or for a specific collection defradb client schema show book:

type Book {
    name: String
    rating: Float
    author: Author
    publisher: Publisher
}

Alternatives considered

No response

Additional context

No response