FR: let NormalisableRange constructor (the one with three mapping functions) have an interval parameter

Feature Requests
1

The current NormalisableRange constructor (the one with three mapping functions) does not support an interval parameter.

NormalisableRange (ValueType rangeStart,
                   ValueType rangeEnd,
                   ValueRemapFunction convertFrom0To1Func,
                   ValueRemapFunction convertTo0To1Func,
                   ValueRemapFunction snapToLegalValueFunc = {}) noexcept

However, as the interval value is used by `SliderAttachment`, I have to first create the range and then set its interval value, which is a bit inconvinient. Could we another constructor like this:

NormalisableRange (ValueType rangeStart,
                   ValueType rangeEnd,
                   ValueType intervalValue,
                   ValueRemapFunction convertFrom0To1Func,
                   ValueRemapFunction convertTo0To1Func,
                   ValueRemapFunction snapToLegalValueFunc = {}) noexcept