Add prod tsconfig for lib output

[mmkal]

@papb this is a pattern I've found useful in a few projects now.

• Have a tsconfig.json which includes all source code but has noEmit: true so is only used for checking
• Have a tsconfig.lib.json which only includes src, and extends tsconfig.json with noEmit: false. This is used to produce the actual library output.
• tsc -p tsconfig.json is part of the lint step. It makes sure all the code in the project is ok. src, test, examples etc.
• tsc -p tsconfig.lib.json is the build step.

The benefits are:

• All type errors are caught by npm run lint. Here's an example from another PR of a change I had to just remember about since it wasn't flagged by CI (the file is under examples/*, which wasn't included in tsconfig.json: 435f968
• IDEs pick up the correct settings. By default VSCode (and others, I believe), search for a tsconfig.json for settings for typescript hints/red squigglies. One example: this project has strictNullChecks: true, but since tsconfig.json was ignoring test, VSCode wasn't showing null errors. ts-jest still caught them, but it's better DX if the IDE knows what's going on.

[mmkal]

Since this config is used for eslint, it needs to include all files that we run the linter on. We're linting README.md, and the various *.config.js, *rc.js files, so need to add them here.