[misc] Share one license collection script across the UBI images (#8055)

* [self-hosted] Add a UBI image variant for the combined server

OpenShift and other Red Hat environments expect UBI-based images that run
as an arbitrary non-root UID. The proxy and rootless client already ship
-ubi variants; this adds the same for netbird-server, published as
<version>-ubi and ubi-latest for amd64 and arm64.

* [self-hosted] Check the license output path before creating temp files

The existing-output exit ran before the cleanup trap was registered, so it
left the two mktemp files behind.

* [self-hosted] Certify the netbird-server UBI image

Adds netbird-server to the Red Hat certification components. Its Partner
Connect component ID goes in the REDHAT_CERT_ID_NETBIRD_SERVER repository
variable.

* [misc] Share one license collection script across the UBI images

The client, proxy and combined images each carried a near-identical copy of
collect-licenses.sh, and the signal and relay variants would add two more.
The copies differed only in the Go package, build tags, component license
and the proxy's web licenses, which are now options of one script in
release_files/. The client gains the staged write the others already had.

client/collect-licenses.sh

@@ -1,77 +0,0 @@
-#!/bin/sh
-set -eu
-
-if [ "$#" -lt 2 ]; then
-	printf '%s\n' "usage: $0 OUTPUT_DIRECTORY GOARCH..." >&2
-	exit 2
-fi
-
-repo_root=$(CDPATH= cd -- "$(dirname "$0")/.." && pwd)
-output_name=$(basename "$1")
-if [ -z "$output_name" ] || [ "$output_name" = "." ] ||
-	[ "$output_name" = ".." ] || [ "$output_name" = "/" ]; then
-	printf '%s\n' "OUTPUT_DIRECTORY must name a directory" >&2
-	exit 2
-fi
-output_parent=$(CDPATH= cd -- "$(dirname "$1")" && pwd)
-output="$output_parent/$output_name"
-shift
-modules=$(mktemp "${TMPDIR:-/tmp}/netbird-client-licenses.modules.XXXXXX")
-sorted_modules=$(mktemp "${TMPDIR:-/tmp}/netbird-client-licenses.sorted.XXXXXX")
-trap 'rm -f "$modules" "$sorted_modules"' EXIT HUP INT TERM
-
-if [ -e "$output" ] || [ -L "$output" ]; then
-	printf 'output directory already exists: %s\n' "$output" >&2
-	exit 1
-fi
-mkdir "$output"
-mkdir "$output/third_party"
-
-cp "$repo_root/LICENSE" "$output/BSD-3-Clause.txt"
-
-cd "$repo_root"
-for arch in "$@"; do
-	GOOS=${GOOS:-linux} GOARCH="$arch" CGO_ENABLED=${CGO_ENABLED:-0} \
-		go list -deps -f '{{with .Module}}{{if .Replace}}{{.Replace.Path}}{{"\t"}}{{.Replace.Version}}{{"\t"}}{{.Replace.Dir}}{{else}}{{.Path}}{{"\t"}}{{.Version}}{{"\t"}}{{.Dir}}{{end}}{{end}}' -tags load_wgnt_from_rsrc ./client >>"$modules"
-done
-LC_ALL=C sort -u "$modules" >"$sorted_modules"
-
-goroot=$(go env GOROOT)
-for term in LICENSE PATENTS; do
-	if [ ! -f "$goroot/$term" ]; then
-		printf 'missing Go standard-library term: %s\n' "$goroot/$term" >&2
-		exit 1
-	fi
-	cp "$goroot/$term" "$output/Go-$term"
-done
-
-while IFS='	' read -r module version module_dir; do
-	[ -n "$module" ] || continue
-	[ "$module" = "github.com/netbirdio/netbird" ] && continue
-
-	if [ -z "$version" ] || [ ! -d "$module_dir" ]; then
-		printf 'cannot collect terms for module %s at version %s\n' "$module" "$version" >&2
-		exit 1
-	fi
-
-	destination="$output/third_party/$module/$version"
-	mkdir -p "$destination"
-	printf 'module: %s\nversion: %s\n' "$module" "$version" >"$destination/MODULE"
-
-	found=false
-	for term in \
-		"$module_dir"/LICENSE* "$module_dir"/License* "$module_dir"/license* \
-		"$module_dir"/LICENCE* "$module_dir"/Licence* "$module_dir"/licence* \
-		"$module_dir"/COPYING* "$module_dir"/Copying* "$module_dir"/copying* \
-		"$module_dir"/NOTICE* "$module_dir"/Notice* "$module_dir"/notice* \
-		"$module_dir"/PATENTS* "$module_dir"/Patents* "$module_dir"/patents*; do
-		[ -f "$term" ] || continue
-		cp "$term" "$destination/"
-		found=true
-	done
-
-	if [ "$found" = false ]; then
-		printf 'no root license terms found for module %s at %s\n' "$module" "$module_dir" >&2
-		exit 1
-	fi
-done <"$sorted_modules"