Build a data structure for a reaction tree

[yauhen-karmyzau]

Develop an algorithm that can build a reaction tree from a list of reactions, using the hash code or the ExactMatch method to match the reactants and products.

AC:

• Only data structure to represent tree is expected as outcome.
• it's a technical task (manual testing isn't required)
• Unit tests are in scope.
  see attached for tests to be added (simple use cases with different input RDF)

tests_reaction_tree.pptx

output can be ket files (without coordinates) or unit test with output each tree

tree:

nodes:
    node1: r1
    node2: r2
    node3: r3, p1
    node4: p2

edges:
    node1, node2

[ivanmaslow]

This is a technical task, testing will be in scope of #2128.
Tests aren't required here.