Publish TypeScript type declarations in Feast UI package

[peruukki]

Is your feature request related to a problem? Please describe.
TypeScript declarations are not available for Feast UI components exported from @feast-dev/feast-ui. If you are using it as a module in a TypeScript project, you need to write the type definitions manually or treat the code as untyped.

Describe the solution you'd like
Declaration files could be bundled in the package, see TypeScript's Publishing page.

Describe alternatives you've considered
Adding type definitions to DefinitelyTyped (i.e. @types/feast-dev__feast-ui) is also possible, but bundling them seems easier since Feast UI already uses TypeScript. Bundled types are also easier to maintain and a better experience for the package consumer.