執行自訂指令組合，以便充分運用 fx -i (疊代模式)
usage: fx [-i] run-script "<command>"
`<command>` can be any command that would be valid as a single line at a shell prompt.
For example,
- Arbitrary shell commands: `fx -i run-script "ls | grep fuchsia"`
- Fuchsia commands: `fx -i run-script "ffx emu stop && fx build && ffx emu start"`
- Independent commands: `fx -i run-script "ls; find . -name test.rs"`
Passing a regular shell script is not supported.