Macro: Enumeration of cyclic chains

[olganaz]

Background
Cyclic chains differ from linear chains by lacking of the explicit chain beginning

Requirements

1. If there is a chain in which it is impossible to specify the first monomer this chain should be considered as cyclic.

Reminder [#3222]
The system shall start enumeration from the monomer, which has occupied R2 attachment point and:

• no R1 attachment point
• free R1 attachment point
• occupied R1 attachment point with the bond R1-Ri, i<>2

2. If the chain is already enumerated and the "cyclic" bond (between R1 of the first monomer and the R2 of the last monomer) is established, then enumeration of monomers should not be changed.
3. Enumeration should be also maintained while switching between different views (flex/snake/sequence)
4. If the cyclic structure is imported from file then the top left monomer in the structure should be considered as the first one.
   - Subsequently, the numbering of monomers should continue along the R2-R1 bonds as described in the task #3222 until the monomer numbered as '1' is met.

Additional context
Related bug #3855