OnProgressParameters isn't exported on pdf.d.ts

[robmv]

Other PDFDocumentLoadingTask callbacks have their corresponding parameters types exported like PasswordResponses and UNSUPPORTED_FEATURES but not OnProgressParameters.

OnProgressParameters should be exported as is part of the API exposed by PDFDocumentLoadingTask.

By the way, PDFDocumentLoadingTask callbacks are using a Function signature without defining the parameter type. I think it should be added but don't know the reason it wasn't. Do other languages beside TypeScript consume the type files and don't understand a better signature?