Add data-testID attributes to monomers, atoms, bonds and connection points on Macromolecules canvas

[AlexeyGirin]

Background
Now we have some difficulties with getting locators on UI elements on the canvas. Unfortunately - not all elements (e.g. monomers) has the same internal structure (in terms of HTML code) that creates difficulties in identifying such elements.

Solution
Add data-testID attributes (at least - they should be unique for element type) to monomers, atoms, bonds and connection points on Macromolecules canvas