feat(Apollo): Add constructor to ApolloAmplifyConnector for directly specifying connection information

[mattcreaser]

• PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:
ApolloAmplifyConnector was created to read AppSync connection information from amplify_outputs.json, but some customers who do use Amplify but do not have a Gen2 configuration file (e.g. existing Gen1 customers) may also want to use this class. They already could use the companion functions, but this new constructor makes it possible for them to use the convenience authorizer factories instead.

So now a Gen1 customer can do the following:

val connector = ApolloAmplifyConnector(
    endpointUrl = "https://example1234567890123456789.appsync-api.us-east-1.amazonaws.com/graphql",
    region = "us-east-1",
    apiKey = "[YOUR_API_KEY]"
)

val apolloClient = ApolloClient.Builder()
    .appSync(connector.endpoint, connector.apiKeyAuthorizer())
    .build()

How did you test these changes?
Unit test

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)

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

[tylerjroach]

BR 1 API Change approved.