feat: Add new run command

With this new command it adds the ability to run custom commands
and/or scripts right from the terminal.  Examples have been added
to the README and likewise example scripts under the new `examples`
directory.

As a quick overview, before executing anything, we inherit an array
of enviroment variables that contain relevent information of the
package update(s), for example

portsync run 'echo $PACKAGE_ORIGIN: Update to $PACKAGE_LATEST'

Will yield something of the likings:

misc/broot: Update to 1.2.0
devel/gh: Update to 1.36.1

README.md

@@ -101,6 +101,15 @@ Or even be able to output updates in a particular file format, such as JSON
 portsync fetch -f '{"origin": "%o", "current": "%v", "latest": "%l"}'
 ```
 
+Run arbitrary commands and/or scripts
+```sh
+portsync run -o misc/broot examples/genjson
+{"origin": "misc/broot", "version": "1.25.0", "newversion": "1.25.1"}
+portsync run 'if [ $PACKAGE_ORIGIN == "misc/broot" ]; then echo "$PACKAGE_ORIGIN!"; fi'
+misc/broot!
+```
+See [examples](examples) for example scripts.
+
 Happy hacking!
 
 ## License

cmd/run.go

@@ -0,0 +1,41 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) Lewis Cook <lcook@FreeBSD.org>
+ * All rights reserved.
+ */
+package cmd
+
+import (
+	"os"
+	"os/exec"
+	"strings"
+
+	. "github.com/lcook/portsync/internal/fetcher"
+	. "github.com/lcook/portsync/internal/util"
+	"github.com/spf13/cobra"
+)
+
+var runCmd = &cobra.Command{
+	Use:   "run",
+	Short: `Run local script or command`,
+	Long:  `Run local script or command with inherited package enviroment variables.`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		packages, err := GetPackages(Portscout{})
+		if err != nil {
+			return err
+		}
+		for _, _package := range *packages {
+			SetPkgEnv(_package)
+			c := exec.Command("sh", "-c", strings.Join(args, " "))
+			c.Stdout = os.Stdout
+			c.Stderr = os.Stderr
+			_ = c.Run()
+		}
+		return nil
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(runCmd)
+}

examples/genjson

@@ -0,0 +1,5 @@
+#!/usr/bin/env sh
+#
+# Generate JSON output of available package updates.
+#
+echo '{"origin": "'$PACKAGE_ORIGIN'", "version": "'$PACKAGE_VERSION'", "newversion": "'$PACKAGE_LATEST'"}'

examples/poudriere_qa

@@ -0,0 +1,61 @@
+#!/usr/bin/env sh
+#
+# In this script we create a differential patch of unstaged changes
+# of a port from our local ports repository, and make an attempt
+# to apply the patch to a remote server containing a Poudirere
+# ports tree.
+#
+# Assuming the patch applied cleanly, run `testport` for each of
+# the jails defined on the particular port we made changes to.
+# Report back build status when completed.
+#
+# Usual workflow may be as follows:
+# $ portsync update -o foo/bar
+# $ portsync run -o foo/bar examples/poudriere_qa
+# $ git add foo/bar/*
+# $ git commit -m "foo/bar: Update to latest version"
+# 
+buildhost="host@example.org"  # Domain or IP of remote build host.
+buildport=  # ssh port of remote build host.
+jails="your jails"  # List of jails.  E.g., "12-amd64 13-amd63".
+porttree=  # Tree name of Poudriere ports tree.
+portdir=   # Directory to Poudirere ports repository.
+
+package="$PACKAGE_ORIGIN"
+
+_port=${buildport:-"22"}
+if ! ssh -o BatchMode=yes -o ConnectTimeout=10 -p\
+  "$_port" $buildhost "exit"; then
+  printf "\nCould not connect to build host.  Diagnose issue and try again\n"
+  exit 1
+fi
+
+_dir=${portdir:-"/usr/local/poudriere/ports/default"}
+_tree=${porttree:-"default"}
+if ! _diff=$(git -C "$PACKAGE_ROOT" diff "$package"\
+  | ssh -o BatchMode=yes -p "$_port" $buildhost "git -C $_dir apply -p0"); then
+  echo "$_diff"
+  echo "Unable to apply patch to $package on build host cleanly"
+  echo "Verify the integrity of the remote ports tree repository and try again"
+  exit 1
+fi
+
+_failed=
+_built=
+for j in $jails; do
+  if ! ssh -o BatchMode=yes -p "$_port" $buildhost\
+    "poudriere testport -j $j -p $_tree $package"; then
+    _failed="$_failed $j"
+    continue
+  _built="$_built $j"
+  fi
+done
+
+# Restore remote ports tree to a clean state.
+ssh -o BatchMode=yes -p "$_port" $buildhost "git -C $_dir restore $package"
+
+echo ===================================================
+printf "===> Poudriere results for %s\n" "$package"
+
+[ -n "$_built"  ] && echo "=>> Built:$_built"
+[ -n "$_failed" ] && echo "=>> Failed:$_failed" && exit 1

examples/updates

@@ -0,0 +1,5 @@
+#!/usr/bin/env sh
+#
+# Basic script printing the latest package version.
+#
+echo "[$PACKAGE_ORIGIN@$PACKAGE_VERSION] New update to $PACKAGE_LATEST"