Add rule for trailing commas

[nishtahir]

We should add a new rule for trailing commas?

Reference eslint implementation
https://eslint.org/docs/rules/comma-dangle

For example, the following function

function sampleFunction() as object
    if GetGlobalAA().user = invalid then
        user = {
            _name : "",
        }
        GetGlobalAA()["user"] = user
    end if
    return invalid
end function

would warn about the trailing comma , in the code block.

[nishtahir]

Related to #64