Support export of user data #14
Description
There are several scopes.
Export of files in a workspace is straightforward - just download an archive of all files. Although this can be made better from UI point of view - do not create this file inside of the workspace file system, which may exceed its quota, and instead have some button "Download this Workspace".
Export of TimeTravel or logs related to a particular workspace, as JSON files or databases. These are standard formats and we don't have to provide extra tools to view or convert them.
Export of "Account" meaning its preferences and everything else that is not tied to a particular workspace, in particular - all transactions. JSON file or a standard database should work as well as a format.