feat(kernel): implement generation-based capability revocation with proofs and tests

crates/domain/src/memory/mod.rs

@@ -58,6 +58,10 @@ impl MemoryRegion {
     pub fn generation(&self) -> &Generation {
         &self.generation
     }
+
+    pub fn revoke(&mut self) {
+        self.generation = self.generation.next();
+    }
 }
 
 pub struct RegionTable {
@@ -82,6 +86,10 @@ impl RegionTable {
         self.regions.get(id.raw() as usize).and_then(|s| s.as_ref())
     }
 
+    pub fn get_mut(&mut self, id: RegionId) -> Option<&mut MemoryRegion> {
+        self.regions.get_mut(id.raw() as usize).and_then(|s| s.as_mut())
+    }
+
     pub fn remove(&mut self, id: RegionId) -> Option<MemoryRegion> {
         self.regions.get_mut(id.raw() as usize).and_then(|s| s.take())
     }