gh cli alias importer

gh_alias_importer

Currently there is no command to import gh alias easily, so this is workaround

1. Export the gh alias

```bash
$ gh alias list > gh_aliases.txt
```

2. create import script

create `gh_alias_import.sh`

```bash
#!/bin/bash
TARGET=$1
echo "import gh aliases..."
while read line ; do
  ALIAS=$(echo $line | cut -f 1 -d:)
  COMMAND=$(echo $line | cut -f 2 -d: | sed -e 's/^\s*//')
  echo "execute: gh alias set $ALIAS \'$COMMAND\'"
  gh alias set $ALIAS "$COMMAND"
done < $1
echo "finish!"
```

3. Exec script

```
$ sh gh_alias_import.sh gh_aliases.txt
```