Add support for different DB drivers

[Pavel910]

This PR contains many improvements with focus on support for different DB drivers (#575).
Along the way I also worked on Windows support, so you can setup our repo and deploy everything on Windows (closes #620).

To enable support for different drivers we had to push the usage of plugins a little bit further, here is an example of an apollo service configuration (see the apolloService key):

files:
  component: "@webiny/serverless-files"
  inputs:
    region: ${vars.region}
    bucket: ${vars.bucket}
    functions:
      apolloService:
        memory: 512
        timeout: 10
        uploadMinFileSize: 0 # 0 MB
        uploadMaxFileSize: 26214400 # 25 MB
        plugins:
          - factory: "@webiny/api-plugin-create-apollo-handler"
            options: ${vars.apollo}
          - factory: "@webiny/api-plugin-commodo-mongodb"
            options: ${vars.commodo}
          - factory: "@webiny/api-security/plugins/service"
            options: ${vars.security}
          - "@webiny/api-files/plugins"
          - "@webiny/api-plugin-files-resolvers-mongodb"
      downloadFile:
        memory: 512
        timeout: 10
      imageTransformer:
        memory: 1024
        timeout: 10

A few things to note here:

1. Apollo handler is now a plugin as well, so you can control how the Apollo handler is being created.
2. The Commodo driver for MongoDB is now also a plugin @webiny/api-plugin-commodo-mongodb. This way you can easily replace the driver plugin.
3. @webiny/api-plugin-files-resolvers-mongodb - this is a set of plugins for data resolvers that are using some DB native constructs, like Mongo aggregate. We've implemented those resolvers via plugins, so when you replace a DB driver, you'll also have to provide a set of plugins to resolve the data using your database of choice.

[adrians5j]

Awesome stuff! 🚀