Merge branch 'ps/cat-file-remote-object-info'

Merge branch 'ps/cat-file-remote-object-info'

The 'remote-object-info' command has been added to 'git cat-file
--batch-command', allowing clients to request object metadata
(currently size) from a remote server via protocol v2 without
downloading the entire object.  Format placeholders are dynamically
filtered on the client based on server-advertised capabilities,
returning empty strings for inapplicable or unsupported fields.

* ps/cat-file-remote-object-info:
  cat-file: make remote-object-info allow-list adapt to the server
  cat-file: add remote-object-info to batch-command
  transport: add client support for object-info
  serve: advertise object-info feature
  protocol-caps: check object existence regardless of the attributes requested
  fetch-pack: move fetch initialization
  connect: make write_fetch_command_and_capabilities() more generic
  fetch-pack: move write_fetch_command_and_capabilities() to connect.c
  fetch-pack: use unsigned int for hash_algo variable
  fetch-pack: drop the static advertise_sid variable
  t1006: extract helper functions into new 'lib-cat-file.sh'
  cat-file: declare loop counter inside for()
  transport-helper: fix memory leak of helper on disconnect