cvmts: Delete cgroup on VM stop

Makes clean shutdown with systemd actually work.

I've also made superqemu version a SemVer thing so that we don't need to bump it as often, only on a major or minor bump.

cvmts/src/util/cgroup.ts

@@ -1,7 +1,7 @@
 // Cgroup management code
 // this sucks, ill mess with it later
 
-import { appendFileSync, existsSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';
+import { appendFileSync, existsSync, mkdirSync, readFileSync, rmdirSync, writeFileSync } from 'node:fs';
 import path from 'node:path';
 
 export class CGroupController {
@@ -46,6 +46,16 @@ export class CGroup {
 		return false;
 	}
 
+	DeleteSubgroup(name: string): void {
+		let subgroup_root = path.join(this.path, name);
+		if (!this.HasSubgroup(name)) {
+			throw new Error(`Subgroup ${name} does not exist`);
+		}
+
+		//console.log("Deleting subgroup", name);
+		rmdirSync(subgroup_root);
+	}
+
 	// Gets a CGroup inside of this cgroup.
 	GetSubgroup(name: string): CGroup {
 		// make the subgroup if it doesn't already exist