Redwood: Convert `@redwoodjs/web` to TypeScript

[peterp]

The current package has type definitions contributed by @Burnsy, but we would like to convert the entire package to TypeScript.

• [x] Convert project to transpile TS and JS files. @peterp #1232
• [x] Convert RedwoodProvider(in progress #1291)
• [x] Convert FatalErrorBoundary(in progress #1273)
• [x] Convert createGraphQLClient
• [x] Convert GraphQLProvider
• [ ] Convert FlashComponent (in progress #1312)
• [ ] Convert src/packages/web/config.js (in progress #1312)
• [ ] Remove allowJs from tsconfig in web package.

/cc @kimadeline

[Burnsy]

Maybe flash should be it's onwn module as it can be quite useful without the forms. 😌 ie for notifications.

[peterp]

@Burnsy It's so difficult to strike a balance here, maybe we can just keep it in.

[thedavidprice]

TeamTS FTW 🚀

[peterp]

Whoops, we need to open this again, since we need to convert the Flash component.