Refactor: deconstructing the /rmrk folder structure

[petersopko]

following from @roiLeo comment here:

• Folder structure #3068 (comment)

some of the points I'd like to see done here:

• deconstructing the /rmrk folder structure // now also /bsx folder since we don't want chains there
• move all things related to collection into a new folder
• clean up /rmrk/Gallery/

Please look for dead / old components (I'm sure I saw whole component which was not doing anything somewhere in /rmrk), non used variables -> in general, let's try to reduce the amount of code and make stuff cleaner and easier to read