Merge branch 'ab/serve-cleanup' into jk/reduce-malloc-in-v2-servers

* ab/serve-cleanup: upload-pack: document and rename --advertise-refs serve.[ch]: remove "serve_options", split up --advertise-refs code {upload,receive}-pack tests: add --advertise-refs tests serve.c: move version line to advertise_capabilities() serve: move transfer.advertiseSID check into session_id_advertise() serve.[ch]: don't pass "struct strvec *keys" to commands serve: use designated initializers transport: use designated initializers transport: rename "fetch" in transport_vtable to "fetch_refs" serve: mark has_capability() as static