fix: test do not accept multple line string on linux

[CSUwangj]

What: using shell-quote to deal with multiple line string test case

Why and How: current plugin accept multiple line string test case, but will lead to run time failure which said something like

balabala" is not a string

it's because arguments pass to leetcode-cli will be something like 123"\n"123, using shell-quote will resolve problem, for the "123"\n"123", it will turned into "'\"123\"\\n\"123\"'".

Beware that this solution only apply for Linux platform, I tested in my Ubuntu machine.