TS Language Server: JSX Attribute types autocompletion

<!-- 🚨 STOP 🚨 𝗦𝗧𝗢𝗣 🚨 𝑺𝑻𝑶𝑷 🚨 Half of all issues filed here are duplicates, answered in the FAQ, or not appropriate for the bug tracker. Please read the FAQ first, especially the "Common Feature Requests" section. --> ## Search Terms <!-- List of keywords you searched for before creating this issue. Write them down here so that others can find this suggestion more easily --> - autocomplete - autocomplete proptypes - autocomplete jsx attribute types - proptypes - jsx intellisense ## Suggestion <!-- A summary of what you'd like to see added or changed --> The TS Language Server should have proper insert text mechanisms to handle react props. There are maybe 4 Scenarios in which we can type PropTypes in React/JSX ## Use Cases <!-- What do you want to use this for? What shortcomings exist with current approaches? --> This would be used to make editing experiences much quicker, especially in react/JSX markup. Webstorm has this feature by default. I would like this feature added to VSCode so I can continue to use a snappier editor, while having just as important intellisense features in it. That and almost 100% of my coworkers also use VSCode, so I want to use the same tools they are. Shortcomings with current Approach: The current way would be to have auto complete suggest prop types as you type them, or with the ctrl + space key shortcut. You would have to do this for every required prop type, which is a significant slow down. If every required prop type is auto inserted I never have to worry about it (and won't have to worry about required props, even during compile time!) ## Examples <!-- Show how this would be used and what the behavior would be --> 1. `const Component = (props: PropDefinition) => <JSX />` 1. `const Component: React.FC<PropDefinition> = (props) => <JSX />` 1. `class MyComponent extends React.Component<PropDefinition>` 1. `MyComponent.propTypes = PropTypesObject` even though the fourth case would only ever occur in Vanilla JS files, I w…