Rename plugin to nodejs

This plugin should be renamed to `cloudformation-cli-nodejs-plugin`. Here are the reasons:

1. All the current CloudFormation CLI plugins are the runtime used by the provider backend: Java, Python and Go. It makes sense to call them languages when the runtime and the programming language have the same name. As you see in the [AWS Lambda runtimes documentation](https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html), there is no TypeScript or JavaScript runtime, but rather Node.js.
2. In the future, we could be creating the different languages in a single GitHub repository. Because you can always compile the TypeScript into JavaScript, they can share the same codebase. The following would be a list of possible language plugins to be managed from a single repository and one PyPI library:
a. TypeScript (Node.js 14.x): code scaffolding for TypeScript language but running on Node.js 14 compute.
b. TypeScript (Node.js 12.x): the same as above, but on Node.js 12.
c. JavaScript (Node.js 14.x): code scaffolding for JavaScript language but running on Node.js 14 compute.
d. JavaScript (Node.js 12.x): the same as above, but on Node.js 12.