codeintel: Add num_parts and uploaded_parts to lsif_uploads table

Created by: efritz

This is a step to simplify the effort in https://github.com/sourcegraph/sourcegraph/pull/10456, which implements RFC 143: Multipart uploads.

This adds two new fields to the lsif_uploads table: num_parts and uploaded_parts and adds the uploaded value to the LSIF state enum. The first field is the number of expected parts to be uploaded and the later is the index of parts that have already been uploaded. Once the length of the array is the number of expected parts, the parts can be stitched together into a single upload on the backend.

The current behavior is to populate these fields with 1 and [0], as multipart uploads are not yet implemented. These values are correct for uploads that have a single payload.