projects-dir.mk: Remove "-l user" in ssh-wrapper.sh

By the time projects-dir.mk is used during onboarding, it's already cloned, and so is jw-pkg in all its glory. So better use a ssh-wrapper.sh directly under jw-pkg's version control instead of plainly generating one with echo some-script-logic > ssh-wrapper.sh.
This has the main benefit of allowing a more elaborate script.  The one added by this commit removes "-l user" from remotes which have a standard-user@gitserver form, typically because they differentiate users via their SSH pubkeys only, and which would deny access if both -l user and standard-user@ were specified.
ssh-wrapper.sh still needs to be a target which is updated by a recipe, because the version found in jw-pkg can't be trusted to be executable during bootstrapping, because "make all" has not run, yet.
Signed-off-by: Jan Lindemann <jan@janware.com>

scripts/ssh-wrapper.sh

@@ -0,0 +1,62 @@
+#!/bin/bash
+
+# JW_PKG_SSH_EXTRA_OPTS in the context of CI can contain "-l someuser".  For
+# the ssh login to a remote ssh://otheruser@gitserver.com, this runs the ssh
+# command "ssh -l someuser otheruser@gitserver.com".  Since with openssh, -l
+# takes precedence of the @, ssh tries to authenticate as someuser against
+# gitserver, and is rightly denied access.
+#
+# That case happens with the janware's pub remote, so the -l needs to be
+# removed from JW_PKG_SSH_EXTRA_OPTS if a remote with a username@ prefix from
+# the Git configuration hits this script, and that's what most of its logic
+# does.
+
+run_ssh()
+{
+	local has_user_at_host=0
+	local arg
+	for arg in "$@"; do
+		case "$arg" in
+			-*)
+				;;
+			?*@?*)
+				has_user_at_host=1
+				break
+				;;
+		esac
+	done
+
+	local -a extra_opts
+	read -r -a extra_opts <<< "${JW_PKG_SSH_EXTRA_OPTS:-}"
+
+	if (( has_user_at_host )); then
+		local -a filtered_opts=()
+		local skip_next=0
+		local opt
+		for opt in "${extra_opts[@]}"; do
+			if (( skip_next )); then
+				skip_next=0
+				continue
+			fi
+
+			case "$opt" in
+				-l)
+					skip_next=1
+					;;
+				-l?*)
+					;;
+				*)
+					filtered_opts+=("$opt")
+					;;
+			esac
+		done
+
+		extra_opts=("${filtered_opts[@]}")
+	fi
+
+	[[ "${JW_PKG_VERBOSE:-false}" = "true" ]] && set -x
+
+	exec /usr/bin/ssh "${extra_opts[@]}" "$@"
+}
+
+run_ssh "$@"