Backmerge: #1774 Save to CDX converts aromatic benzene ring to dashed ring

[AliaksandrDziarkach]

Add kCDXProp_Bond_Display2 property saving. Fix UT

Backmerge request

• [ ] PR name follows the pattern Backmerge: #1234 – issue name
• [ ] PR is linked with the issue
• [ ] base branch (master or release/xx) is correct
• [ ] code contains only backmerge changes