Add command `cmsis-solution.getSvdFile` (won't fix)

[ReinhardKeil]

Some extensions or tools may need access to the SVD file of the current target device.

Therefore we should add a new command

cmsis-solution.getSvdFile Path and name of the SVD file of Active Target

[ReinhardKeil]

This seems not to work for every device, as devices may have SVD files that are specific to a pname (processor).

Therefore, this ticket is parked. The proper way is to use the cbuild-run.yml file which can be already accessed.

[jkrech]

Note that this has been addressed in the CMSIS Debugger extension which now reads this information from the cbuild-run.yml file.
Open-CMSIS-Pack/vscode-cmsis-debugger#151