Add exception to rule S4144 when the function body is small.

[francoismora]

Fixes SonarSource/SonarJS#3288

This PR changes the rule to look only at function declaration, method definition and variable declarators:

// Function declarations
function foo() {
}

class Foo {
  // Method definitions
  foo() {
  }
}

// Variable declarators:
const foo = () => {
};

We can expect true positives to be ignored with this:

[sonarcloud]

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