Project: Use variable level FASTT defaults in chart value defaults chain

[danyx23]

This is the follow up project to finish the bulk FASTT editor (#1224). After making Bulk FASTT editing work on the chart level and fixing the remaining UI issues in the editor itself, the main remaining issue is to make use of the variable level defaults. This encompasses the following:

• [ ] Use variable annotations and version them
  • [ ] Add versioning and reverting to previous version to variable annotations
  • [ ] Use variable annotations as defaults when creating new charts
  • [ ] Change "inheritance" of chart config properties so they include the variables (e.g. axis labels) in a way that can be overridden. This needs some design to verify where this applies.
  • [ ] Migration of chart config to variable config for variables only charted once