text: Title: Add support for filtering by Json values
  Body: ## Problem
  
  <!-- A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] -->
  
  Prisma supports [filtering by the values of json fields](https://www.prisma.io/docs/reference/api-reference/prisma-client-reference#json-filters), we should support it too.
  
  ## Suggested solution
  
  <!-- A clear and concise description of what you want to happen. -->
  
  As the syntax for json filtering differs between database connectors, we should either create a wrapper that normalizes values or leave it up to the user like prisma does.
  
  ```py
  user = await client.user.find_first(
    where={
      'pets': {
        'path': JsonPath('favourite', 'breed'),
        'equals': 'Parson Russell Terrier',
      },
    },
  )
  ```
  
  PostgreSQL
  
  ```py
  user = await client.user.find_first(
    where={
      'pets': {
        'path': ['favourite', 'breed'],
        'equals': 'Parson Russell Terrier',
      },
    },
  )
  ```
  
  MySQL
  
  ```py
  user = await client.user.find_first(
    where={
      'pets': {
        'path': '$.favourite.breed',
        'equals': 'Parson Russell Terrier',
      },
    },
  )
  ```
  
  ## Additional context
  
  <!-- Add any other context or screenshots about the feature request here. -->
  
  [full json filter reference](https://www.prisma.io/docs/reference/api-reference/prisma-client-reference#json-filters)
  [working with json fields](https://www.prisma.io/docs/concepts/components/prisma-client/working-with-fields/working-with-json-fields)
  [MySQL syntax](https://dev.mysql.com/doc/refman/8.0/en/json.html#json-path-syntax)
  [PostgreSQL json](https://www.postgresql.org/docs/11/functions-json.html)
  