Use composite actions in CI (#65)

* Attempt composite actions in CI

* Remove needs monero-daemon for the action

* Correct actions folder layout

* Remove empty inputs/outputs, add shell

* Try moving env declaration spot

* Remove usage of env

* Cached Rust composite action

* Replace [] with ""

Remove empty outputs

.github/actions/monero/action.yml

@@ -0,0 +1,38 @@
+name: monero-regtest
+description: Spawns a regtest Monero daemon
+
+runs:
+  using: "composite"
+  steps:
+    - name: Monero daemon cache
+      id: cache-monerod
+      uses: actions/cache@v3
+      with:
+        path: monerod
+        key: monerod-${{ runner.os }}-${{ runner.arch }}-v0.17.3.2
+
+    - name: Download the Monero Daemon
+      if: steps.cache-monerod.outputs.cache-hit != 'true'
+      # Calculates OS/ARCH to demonstrate it, yet then locks to linux-x64 due
+      # to the contained folder not following the same naming scheme and
+      # requiring further expansion not worth doing right now
+      shell: bash
+      run: |
+        RUNNER_OS=${{ runner.os }}
+        RUNNER_ARCH=${{ runner.arch }}
+
+        RUNNER_OS=${RUNNER_OS,,}
+        RUNNER_ARCH=${RUNNER_ARCH,,}
+
+        RUNNER_OS=linux
+        RUNNER_ARCH=x64
+
+        FILE=monero-$RUNNER_OS-$RUNNER_ARCH-v0.17.3.2.tar.bz2
+        wget https://downloads.getmonero.org/cli/$FILE
+        tar -xvf $FILE
+
+        mv monero-x86_64-linux-gnu-v0.17.3.2/monerod monerod
+
+    - name: Monero Regtest Daemon
+      shell: bash
+      run: ./monerod --regtest --offline --fixed-difficulty=1 --detach