Citadel -> Verifiable Matcher (2 of N)

Summary:
Now starting to replace it in the code. Started with:
```
rg citadel verifiable_matcher/ -l | xargs sed 's/citadel/verifiable_matcher/g' -i
```
And then fixed up issues, e.g. renamed a few files to make crates work again.

Differential Revision: D53553089

fbshipit-source-id: 5c0c7a3924ddab05c9ded4d41b23deb6258b87f8

supertd/bin/main.rs

@@ -20,7 +20,7 @@ use td_util::tracing::init_tracing;
 enum Args {
     Btd(btd::Args),
     #[cfg(fbcode_build)]
-    Citadel(citadel::Args),
+    Citadel(verifiable_matcher::Args),
     #[cfg(fbcode_build)]
     Ranker(ranker::Args),
     #[cfg(fbcode_build)]
@@ -60,7 +60,7 @@ pub fn main(fb: FacebookInit) -> anyhow::Result<()> {
         Ok(args) => match args {
             Args::Btd(args) => btd::main(args),
             #[cfg(fbcode_build)]
-            Args::Citadel(args) => citadel::main(args),
+            Args::Citadel(args) => verifiable_matcher::main(args),
             #[cfg(fbcode_build)]
             Args::Ranker(args) => ranker::main(args),
             #[cfg(fbcode_build)]