prefer-spread: Add more suggestions for .concat fix

[fisker]

If first argument has no sideEffect, added a new suggestion to test it with Array.isArray()

- [1].concat(foo, 2);
+ [1, ...(Array.isArray(foo) : foo : [foo]), 2]

If there are more unknown arguments, added a new suggestion to spread all unknown arguments

- [1].concat(foo, bar);
+ [1, ...foo, ...bar];