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/build-dependencies/action.yml

@@ -1,6 +1,17 @@
 name: build-dependencies
 description: Installs build dependencies for Serai
 
+inputs:
+  rust-toolchain:
+    description: "Rust toolchain to install"
+    required: false
+    default: stable
+
+  rust-components:
+    description: "Rust components to install"
+    required: false
+    default:
+
 runs:
   using: "composite"
   steps:
@@ -11,6 +22,12 @@ runs:
         solc-select install 0.8.9
         solc-select use 0.8.9
 
+    - name: Install Rust
+      uses: ./.github/actions/cached-rust
+      with:
+        toolchain: ${{ inputs.rust-toolchain }}
+        components: ${{ inputs.rust-components }}
+
     - name: Install WASM toolchain
       uses: actions-rs/toolchain@v1
       with: