fix: allow required uni-directional hasOne with @connection when datastore is disabled

[dpilch]

Description of changes

CLI v11.0.0 introduced creating the model introspection schema at the end of every amplify push. Some customers using the v1 transformer with @connection with DataStore disabled were unable to upgrade to later versions of the CLI and successfully push. The model generation at the end of the push failed with DataStore does not support 1 to 1 connection with both sides of connection as optional field. This error is not applicable to customers not using DataStore. This error would also print the case the connection was required on both sides.

This change removes this restriction from customers not using DataStore.

Currently working (user is not required).

type User @model {
  id: ID!
}
type Session @model {
  id: ID!
  sessionUserId: ID!
  # works when user is not required
  user: User @connection(fields: ["sessionUserId"])
}

Results in following connection info.

{
  kind: 'HAS_ONE',
  associatedWith: {
    type: 'ID',
    isNullable: false,
    isList: false,
    name: 'id',
    directives: []
  },
  associatedWithFields: [],
  connectedModel: { name: 'User', type: 'model', directives: [], fields: [ [Object] ] },
  isConnectingFieldAutoCreated: false,
  targetName: 'sessionUserId',
  targetNames: []
}

Removing the restriction allows to set user as a required field.

type User @model {
  id: ID!
}
type Session @model {
  id: ID!
  sessionUserId: ID!
  # user is required
  user: User! @connection(fields: ["sessionUserId"])
}

Results in the following connection info.

{
  kind: 'HAS_ONE',
  associatedWith: {
    type: 'ID',
    isNullable: false,
    isList: false,
    name: 'id',
    directives: []
  },
  associatedWithFields: [],
  connectedModel: { name: 'User', type: 'model', directives: [], fields: [ [Object] ] },
  isConnectingFieldAutoCreated: false,
  targetName: 'sessionUserId',
  targetNames: []
}

Codegen Paramaters Changed or Added

N/A

Issue #, if available

aws-amplify/amplify-category-api#1419

Description of how you validated changes

• Unit test
• e2e test https://us-east-1.console.aws.amazon.com/codesuite/codebuild/594813022831/projects/amplify-codegen-e2e-workflow/batch/amplify-codegen-e2e-workflow%3A6e0f2996-f724-4536-8b73-e5dad41d18a0?region=us-east-1
• Manual testing with customer schema

Checklist

• PR description included
• yarn test passes
• E2E test run linked
• Tests are changed or added
• Changes are tested using sample applications for all relevant platforms (iOS/android/flutter/Javascript) that use the feature added/modified

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[palpatim]

Should dataStoreEnabled be true here?

Suggested change

	const connectionInfo = (processConnections(field, modelMap.User, modelMap, false) as any) as CodeGenFieldConnectionBelongsTo;
	const connectionInfo = (processConnections(field, modelMap.User, modelMap, true) as any) as CodeGenFieldConnectionBelongsTo;