Add just recipes that trigger release.yml

This adds three recipes to the `justfile`. Two of these recipes
trigger the release workflow.

1. `unique-v-tag`, which delegates to a script, looks at tags that
   point to `HEAD`, reports an error if none, or more than one, of
   them are named starting with `v`, and otherwise outputs the name
   of the unique `v*` tag that it found.

2. `run-release-workflow` triggers the `release.yml` workflow for a
   tag obtained via `unique-v-tag`. By default, it runs it on the
   `GitoxideLabs/gitoxide` repository. This can be adjusted by
   setting the `GH_REPO` environment variable, as usual for `gh`.
   It can also be adjusted by passing an optional argument to the
   recipe (which takes precedence over `GH_REPO` if set).

3. `roll-release` runs `cargo smart-release`, forwarding its
   arguments to it, and then runs the `release.yml` workflow via
   `run-release-workflow`. Because all arguments to `roll-release`
   are passed to `cargo smart-release`, the repository to run
   `release.yml` on cannot be specified as an argument to
   `roll-release`, but `GH_REPO` can still be used to customize it.
   (Also, since `roll-release` is meant to be used when actually
   creating releases and publishing them, it's not expected to run
   on forks nearly as often as the upstream.)

See #1970.

Author: EliahKagan

etc/unique-v-tag.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+set -efu
+IFS=$'\n'
+
+# shellcheck disable=SC2207  # Intentionally splitting. No globbing due to set -f.
+tags=(
+    $(git tag --points-at HEAD -- 'v*')
+)
+
+count="${#tags[@]}"
+if ((count != 1)); then
+    printf '%s: error: Found %d matching v* tags, need exactly 1.\n' "$0" "$count" >&2
+    exit 1
+fi
+
+printf '%s\n' "${tags[0]}"

justfile

@@ -295,3 +295,20 @@ check-mode:
 # Delete `gix-packetline-blocking/src` and regenerate from `gix-packetline/src`
 copy-packetline:
     etc/copy-packetline.sh
+
+# Get the unique `v*` tag at `HEAD`, or fail with an error
+unique-v-tag:
+    etc/unique-v-tag.sh
+
+# Trigger the `release.yml` workflow on the current `v*` tag
+run-release-workflow repo='':
+    optional_repo_arg={{ quote(repo) }} && \
+        export GH_REPO="${optional_repo_arg:-"${GH_REPO:-GitoxideLabs/gitoxide}"}" && \
+        tag_name="$({{ j }} unique-v-tag)" && \
+        printf 'Running release.yml in %s repo for %s tag.\n' "$GH_REPO" "$tag_name" && \
+        gh workflow run release.yml --ref "refs/tags/$tag_name"
+
+# Run `cargo smart-release` and then trigger `release.yml` for the `v*` tag
+roll-release *csr-args:
+    cargo smart-release {{ csr-args }}
+    {{ j }} run-release-workflow