Allow `forbiddenSuffixes` should be case insensitive

[gituserjava]

Current Behavior:
Looks like the forbiddenSuffixes is not checking for fields with different cases.

"FieldDefinition":{
    "forbiddenSuffixes": [
        "ModifiedBy",
        "Modifiedby"
    ]
}

type Product {
id: String,
lastModifiedBy: String
}

type Customer {
id: String,
lastModifiedby: String
}

Expected Behavior:
The library should look for each forbiddenSuffixes irrespective of the case (upper or lower or mixed).