consider adding to typescript codegen config option enumSuffix

in my company we like to suffix graphql types with `QLType` so for example `User` schema type would become `UserQLType`.
typescript type, however, the codegen also suffixes enum values which causes typescript errors.

### expectations :

```gql
enum Rule {
admin
user
}
```
=>
```typescript
export enum RuleQLType {
Admin = 'admin',
User = 'user'
}
```

### Reality:

```gql
enum Rule {
admin
user
}
```
=>
```typescript
export enum RuleQLType {
AdminQLType = 'admin',
UserQLType = 'user'
}
```
=> typescript error:
```
Types of property 'rule' are incompatible.
     Type 'rule' is not assignable to type 'RuleQLType'.
```

enumPrefix exists, but not enumSuffix...

thanks