Sending structure to renderer in molfile format instead of ketcher format

[akolyakov42]

Steps to Reproduce

1. Launch Ketcher
2. Launch DevTools and switch to Network tab
3. Create or load structure to canvas
4. Launch "Copy as image" function (press hotkey or click "Copy as Image" button in "Copy..." dropdown)
5. Click on "render" request in Network tab and switch to Payload tab
6. Check "struct" string

Expected behavior
Client sends structure in ketcher format

Actual behavior
Client sends structure in molfile format

Screenshots

User agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)
AppleWebKit/537.36 (KHTML, like Gecko)
Chrome/98.0.4758.109
Safari/537.36

[karen-sarkisyan]

2 tasks should be perform:

• Switch to ket serializer
• Refactor code responsible for copying structure as image