Improves to TIC/function/function call coverage

[aytey]

We have a few "quality of life" requests from automotive customers:

• We should support (explicitly) function and function call coverage
  -If you just have function coverage, then all we see is the coverage markers on the start of the function
  -If you just have function call coverage, then all we see is the coverage markers on the function calls
• We should support a "callee report"
  • If you have function and function call coverage, we should enable a "callee" report
  • This report is accessible from the call receiver (so the function being called) and allows you to get some kind of report that shows which of calls to this function were exercised
  • If possible, this report should allow you to click on a call instance in the report and this instance should open-up in the VS Code editor
• If you have template instantiation coverage with function coverage, we need an "instances called" report
  • This report shows you which instances of this function were called (e.g., you have two template instances, but foo is only called from one of them, then our report shows which was called and which wasn't)
  • Like the "callee report", this is shown from the function receiver (so the function being called)
• Merging TIC coverage should only show green if a statement/branch/etc. is covered in all instances
  • All lines (if in a function with TIC) should have some marker to allow the user to know they can "open a report" and see the information at the template level for every single "coverable entity"
• It should be possible to choose between "background highlighting" and "gutter markers" for showing the actual coverage
  • Selecting background highlighting should allow for user-configurable background colours
  • I do not think we can only have background highlighting (so no gutter highlighting) because then we cannot show to a user that they can generate reports
• Can we support a way to "jump to uncovered" when in a file
  • It would be nice to be able to jump in the file to the first thing that is not 100% covered