Consolidate GitHub CI actions, split out Monero (#71)

* Consolidate GitHub CI actions, split out Monero

build now includes the specified Rust toolchain/components.

Added a test dependencies action which grabs Foundry and Monero.

Split the Monero v14 job into a matrixed job in its own workflow flow. 
It's now only run when Monero has changes.

* Correct Monero unit/integration tests run timing

Additionally tests a feature-less Monero build.

Also removes a pointless Monero file, which already should have been 
removed, causing this workflow to be triggered.

* Correct exclusion and paths

Updates to FROST should re-run the Monero tests to ensure it didn't 
introduce API incompatibilities.

.github/actions/cached-rust/action.yml

@@ -15,7 +15,7 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - name: Rust cache
+    - name: Rust Cache
       uses: actions/cache@v3
       with:
         path: |