tests/inst: Add destructive test framework

This adds infrastructure to the Rust test suite for destructive
tests, and adds a new `transactionality` test which runs
rpm-ostree in a loop (along with `ostree-finalize-staged`) and
repeatedly uses either `kill -9`, `reboot` and  `reboot -ff`.

The main goal here is to flush out any "logic errors".

So far I've validated that this passes a lot of cycles
using
```
$ kola run --qemu-image=fastbuild-fedora-coreos-ostree-qemu.qcow2 ext.ostree.destructive-rs.transactionality --debug --multiply 8 --parallel 4
```
a number of times.

tests/inst/itest-macro/src/itest-macro.rs

@@ -9,18 +9,57 @@ use quote::quote;
 #[proc_macro_attribute]
 pub fn itest(attrs: TokenStream, input: TokenStream) -> TokenStream {
     let attrs = syn::parse_macro_input!(attrs as syn::AttributeArgs);
-    if attrs.len() > 0 {
-        return syn::Error::new_spanned(&attrs[0], "itest takes no attributes")
+    if attrs.len() > 1 {
+        return syn::Error::new_spanned(&attrs[1], "itest takes 0 or 1 attributes")
             .to_compile_error()
             .into();
     }
+    let destructive = match attrs.get(0) {
+        Some(syn::NestedMeta::Meta(syn::Meta::NameValue(namevalue))) => {
+            if let Some(name) = namevalue.path.get_ident().map(|i| i.to_string()) {
+                if name == "destructive" {
+                    match &namevalue.lit {
+                        syn::Lit::Bool(v) => v.value,
+                        _ => {
+                            return syn::Error::new_spanned(
+                                &attrs[1],
+                                format!("destructive must be bool {}", name),
+                            )
+                            .to_compile_error()
+                            .into();
+                        }
+                    }
+                } else {
+                    return syn::Error::new_spanned(
+                        &attrs[1],
+                        format!("Unknown argument {}", name),
+                    )
+                    .to_compile_error()
+                    .into();
+                }
+            } else {
+                false
+            }
+        }
+        Some(v) => {
+            return syn::Error::new_spanned(&v, "Unexpected argument")
+                .to_compile_error()
+                .into()
+        }
+        None => false,
+    };
     let func = syn::parse_macro_input!(input as syn::ItemFn);
     let fident = func.sig.ident.clone();
     let varident = quote::format_ident!("ITEST_{}", fident);
     let fidentstrbuf = format!(r#"{}"#, fident);
     let fidentstr = syn::LitStr::new(&fidentstrbuf, Span::call_site());
+    let testident = if destructive {
+        quote::format_ident!("{}", "DESTRUCTIVE_TESTS")
+    } else {
+        quote::format_ident!("{}", "NONDESTRUCTIVE_TESTS")
+    };
     let output = quote! {
-        #[linkme::distributed_slice(TESTS)]
+        #[linkme::distributed_slice(#testident)]
         #[allow(non_upper_case_globals)]
         static #varident : Test = Test {
             name: #fidentstr,