Merge branch 'kn/refs-generic-helpers'

Refactor service routines in the ref subsystem backends. * kn/refs-generic-helpers: refs: use peeled tag values in reference backends refs: add peeled object ID to the `ref_update` struct refs: move object parsing to the generic layer update-ref: handle rejections while adding updates update-ref: move `print_rejected_refs()` up refs: return `ref_transaction_error` from `ref_transaction_update()` refs: extract out reflog config to generic layer refs: introduce `ref_store_init_options` refs: remove unused typedef 'ref_transaction_commit_fn'