Support HELM aliases for CHEMs

[ljubica-milovic]

Background

In the light of Pistoia introducing CHEMs with HELM aliases, we need to support them on Ketcher's side -- be able to see them on monomer preview for monomers that already have HELM aliases, and be able to assign a HELM alias to a CHEM in the monomer creation wizard.

Requirements

1. HELM aliases of CHEMs should be visible on monomer preview (both in the library and on canvas).

2. The users should be able to set a HELM alias for a CHEM monomer in the monomer creation wizard.

2.1. The logic from a previous ticket should be followed.