Feature Request: Ability to change the logic of String.parseInitials

[DroidPulkit]

Right now at https://github.com/GetStream/avatarview-android/blob/main/avatarview/src/main/kotlin/io/getstream/avatarview/internal/Extensions.kt#L62 This logic only allows initials i.e. 2 letters in imageview. I think, we should provide an option for end user to write custom logic for parseInitials. Maybe 3 digits, or any any number of digits