UI Features for VariantEffect/mavedb-api#574

This pull request updates the annotated variant download functionality in the ScoreSetView.vue component to improve user experience and reliability. The download process now streams data with progress feedback, allows cancellation, and provides better error handling. The UI has been updated to reflect these changes, including a progress bar and disabling the download button during active downloads.

Annotated Variant Download Improvements:

• The downloadAnnotatedVariants method has been replaced by a new streamVariantAnnotations method, which streams annotated variant data from the backend using the Fetch API and displays a real-time progress bar based on metadata from response headers.
• The download button for annotated variants is now disabled during an active download, and a progress bar is shown below the button to indicate progress.
• Users can now abort an ongoing download via the new abortStream method, which cancels the fetch request and resets the progress UI.

UI and Dependency Updates:

• Added the ProgressBar component from PrimeVue and registered it for use in the component. [1] [2]
• Updated the state to track download progress and control UI feedback (annotatedDownloadInProgress, annotatedDownloadProgress, streamController).

Refactoring and API Usage:

• The download commands for annotated variant options now use the new streaming method instead of the old download method. [1] [2]