Adding Typescript support for JS-SDK
Based on the discussion on the issue https://gitlab.com/gitlab-org/analytics-section/product-analytics/gl-application-sdk-js/-/issues/19, adding TS support for JS-SDK.
Based on the discussion on the issue https://gitlab.com/gitlab-org/analytics-section/product-analytics/gl-application-sdk-js/-/issues/19, adding TS support for JS-SDK.