New pattern submission - Eventbridge bus to Appsync Subscription

[aphilippartd]

To submit a template to the Serverless Patterns Collection, submit an issue with the following information.

IMPORTANT
Patterns are intended to be primarily IaC-focused implementations of 2-4 AWS services, with minimum custom code. They should be commonly used combinations that help developers get started quickly. If you have a utility, demo, or application, submit these to the Serverless Repos Collection instead.

ONLY SUBMIT ONE PATTERN CHANGE PER PR. Multiple patterns or files spanning multiple pattern directories will be automatically rejected.

Patterns may take up to 4-6 weeks to review, test, and merge but there is no SLA and can take significantly longer due to other work the team has.

To learn more about submitting a pattern, read the publishing guidelines page.

1. Use the model template located at https://github.com/aws-samples/serverless-patterns/tree/main/_pattern-model to set up a README, template and any associated code.

2. THIS PROCESS HAS BEEN SIMPLIFIED. All the information below must be provided in the "example-pattern.json" file cloned from the model **

Note the following information for the model:

• Description (intro.text) should be a 300-500 word explanation of how the pattern works.
• Resources should like to AWS documentation and AWS blogs related to the post (1-5 maximum).
• Author bio may include a LinkedIn and/or Twitter reference and a 1-sentence bio.

You must ensure that the sections of the model README.md are completed in full.

GitHub PR for template: #2046