This pull request adds the JSON schema for `cgmanifest.json`.
## FAQ
### Why?
A JSON schema helps you to ensure that your `cgmanifest.json` file is valid.
JSON schema validation is a build-in feature in most modern IDEs like Visual Studio and Visual Studio Code.
Most modern IDEs also provide code-completion for JSON schemas.
### How can I validate my `cgmanifest.json` file?
Most modern IDEs like Visual Studio and Visual Studio Code have a built-in feature to validate JSON files.
You can also use [this small script](https://github.com/JamieMagee/verify-cgmanifest) to validate your `cgmanifest.json` file.
### Why does it suggest camel case for the properties?
Component Detection is able to read camel case and pascal case properties.
However, the JSON schema doesn't have a case-insensitive mode.
We therefore suggest camel case as it's the most common format for JSON.
### Why is the diff so large?
To deserialize the `cgmanifest.json` file, we use [`JSON.parse()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse).
However, to serialize the JSON again we use [`prettier`](https://prettier.io/).
We found that, in general, it gave smaller diffs than the default [`JSON.stringify()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify) function.
Switch to using jsoncpp as our json library. This lets us pretty-print the json file by default, and lets users place comments in the json file.
We will now only re-write the file when the actual logical structure of the json object changes, not only when the serialization changes.
Unfortunately, this will remove any existing ordering of profiles, and make the order random. We don't terribly care though, because when #754 lands, this will be less painful.
It also introduces a top-level globals object to hold all the global properties, including keybindings. Existing profiles should gracefully upgrade.
