Eric W. Biederman authored Sep 26, 2023 and Junio C Hamano committed Sep 26, 2023

As the code is written today index_bulk_checkin only accepts blobs.
Remove the enum object_type parameter and rename index_bulk_checkin to
index_blob_bulk_checkin, index_stream to index_blob_stream,
deflate_to_pack to deflate_blob_to_pack, stream_to_pack to
stream_blob_to_pack, to make this explicit.

Not supporting commits, tags, or trees has no downside as it is not
currently supported now, and commits, tags, and trees being smaller by
design do not have the problem that the problem that index_bulk_checkin
was built to solve.

Before we start adding code to support the hash function transition
supporting additional objects types in index_bulk_checkin has no real
additional cost, just an extra function parameter to know what the
object type is.  Once we begin the hash function transition this is not
the case.

The hash function transition document specifies that a repository with
compatObjectFormat enabled will compute and store both the SHA-1 and
SH...