Make collection iterators fulfill LegacyInputIterator and input_itera…

…tor concept (#626)

* add copy construction and assignment

* add multipass check references bound to the same object

* add type aliases, iterators are LegacyIterator

* add postfix operator, iterators are LegacyInputIterators

* add value-initialization

* use default member initializers

* remove obsolete todos

* add missing semantic requirements checks for concepts

* make dereference const by not updating local object, iterators are std::input_iterators

* clarify lack of operator-> for std::counted_iterator adapting collection iterators

* check ranges concepts

* check algorithms

* move checking unsuported range algorithms to a separate test case

* move checking unsupported iterator concepts to separate test

* add tests for interop with C++23 const_iterator adaptor

* use `colection::mutable_type`

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Co-authored-by: Thomas Madlener <thomas.madlener@desy.de>