Applying psalm immutable + psalm.level=1

[Chemaclass]

Here I'm trying to get rid of the classes' states in order to make them immutable.

For example, the class SegmentedValues had a property lists which it was mutable: the method fromRaw() was mutating that state(lists: array), instead of having that property, why not create a pure function without side effects? So that's what this PR is about. Getting rid of state mutation in favor of pure functions which doesn't have side effects but returning the value that we want.

In order to get rid of the array<array<string, array<string, SegmentInterface>>> return type, I encapsulate each "transaction message" into the class TransactionMessage, which contains exactly all their grouped segments.

TransactionMessage::groupSegmentsByMessage(SegmentInterface...):list<TransactionMessage>

Doing this approach we don't need to rely on arrays offsets to get their values but a method

TransactionMessage::segmentByName(string):array<string, SegmentInterface>

[JesusValera]

Nice way you implement immutability in the classes!