serve: advertise object-info feature

serve: advertise object-info feature

In order for a client to know what object-info components a server can
provide, advertise supported object-info features. This allows a client
to decide whether to query the server for object-info or fetch as a
fallback.

Helped-by: Jonathan Tan <redacted>
Helped-by: Christian Couder <redacted>
Signed-off-by: Calvin Wan <redacted>
Signed-off-by: Eric Ju <redacted>
Signed-off-by: Pablo Sabater <redacted>
Signed-off-by: Junio C Hamano <redacted>