fix: don't erase static modifier when auto-fixing static methods

[mitchell-merry]

Description (What)

Added a check to see if the the function we are changing has the static modifier, and if so, retain it.

Before, it would try to fix methods like:

class MyClass {
  static async someFunc() {
    return something;
  }
}

by doing:

class MyClass {
  someFunc = async () => something;
}

Now it does:

class MyClass {
  static someFunc = async () => something;
}

Justification (Why)

This is broken, now this is fixed

How Can This Be Tested?

Unit tests.