Save Support for RDF Format

[ivanmaslow]

As a User, I want to have the ability to save my data in RDF format, So that I can easily exchange data with other applications that use the same format.

Acceptance Criteria:

1. When I am using the Ketcher application, I should see an option to save my data in RDF V2000 and RDF V3000 format under File format
   menu.
   

2. RDF V2000 and RDF V3000 should be displayed after "SDF" option.

3. When I choose to save my data in RDF format, the application should convert my data into RDF format and save it to the specified location.

4. I should be able to name the RDF file during the save process and the file extension should be .rdf.

5. If a user added multi-tailed arrow to Canvas, the default save option should be changed from MDL Molfile V2000 to MDL Rxnfile V2000 (also MDL Molfile V3000 should be changed to MDL Rxnfile V3000)

6. Saving/loading of reaction with Multi-Tailed Arrow should work as for .RXN with the single arrow:

   • Save a reaction with Multi-Tailed Arrow SDF V2000, SDF V3000, InChlm InChl AuxInfo, InchlKey - the "Convert error! core: is not a base molecule" error is displayed:
     
   • Save a reaction with Multi-Tailed arrow to Daylight SMARTS, Daylight SMILES or Extended SMILES, CML should save the root reaction as it work for reaction with the single arrow in RXN

7. Errors and warnings will be covered in scope of Warning or error messages appear when the user tries to save a Multi-Tailed Arrow to inappropriate formats #5338

[ivanmaslow]

It will be tested in the scope of epam/Indigo#2237, please check this task for more details.