Massive refactor to accommodate RISC-V targets

- Refactored entire codebase (excluding the Insight component) to accommodate multiple target architectures (no longer specific to AVR)
- Deleted 'generate SVD' GDB monitor command - I will eventually move this functionality to the Bloom website
- Added unit size property to address spaces
- Many other changes which I couldn't be bothered to describe here

build/scripts/Targets/TargetDescriptionFiles/Services/ValidationService.php

@@ -606,7 +606,7 @@ class ValidationService
         if ($register->size === null) {
             $failures[] = 'Missing size';
 
-        } elseif ($register->size < 1) {
+        } elseif ($register->size < 1 || $register->size > 8) {
             $failures[] = 'Invalid size (' . $register->size . ')';
         }