New buckets for 0.6.0: small changes

- Fix bucket delete

- fix merge of bucket creation date

- Replace deletable with option in aliases
    Rationale: if two aliases point to conflicting bucket, resolving
    by making an arbitrary choice risks making data accessible when it
    shouldn't be. We'd rather resolve to deleting the alias until
    someone puts it back.

src/garage/cli/cmd.rs

@@ -168,8 +168,8 @@ pub async fn cmd_admin(
 			println!("List of buckets:");
 			let mut table = vec![];
 			for alias in bl {
-				if let Some(p) = alias.state.get().as_option() {
-					table.push(format!("\t{}\t{:?}", alias.name(), p.bucket_id));
+				if let Some(alias_bucket) = alias.state.get() {
+					table.push(format!("\t{}\t{:?}", alias.name(), alias_bucket));
 				}
 			}
 			format_table(table);