Add cargo test dummy_issuer to CI (#25)

# Motivation

Do not add breaking changes to dummy_issuer accidentally.

In this PR, I add the integration tests of the dummy_issuer to the CI.

# Changes

* New workflow "Rust" to build the wasm and execute the tests.

# Tests

Already running in the PR.

# Todos

- [ ] Add entry to changelog (if necessary). Not necessary.

.github/workflows/checks.yml

@@ -1,4 +1,4 @@
-name: CI Checks
+name: JS Library Checks
 
 on:
   pull_request:

.github/workflows/rust.yml

@@ -0,0 +1,49 @@
+name: Cargo Tests
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+    branches: ["main"]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        run: |
+          rustup component add rustfmt
+          rustup component add clippy
+
+      - name: Check Format
+        run: cargo fmt --all -- --check
+
+        # fails if lockfile is out of date
+        # https://users.rust-lang.org/t/check-if-the-cargo-lock-is-up-to-date-without-building-anything/91048/5
+      - name: Cargo Lockfile Check
+        run: cargo update --workspace --locked
+
+      - name: Install PocketIC
+        run: |
+          curl -sL -o pocket-ic.gz https://github.com/dfinity/pocketic/releases/download/4.0.0/pocket-ic-x86_64-linux.gz
+          gzip -d pocket-ic.gz
+          chmod +x pocket-ic
+          echo "POCKET_IC_BIN=$(pwd)/pocket-ic" >> $GITHUB_ENV
+
+      - name: Install ic-wasm
+        run: cargo install ic-wasm --version 0.3.5
+
+      - name: Build Wasm Dummy Issuer
+        working-directory: dummy-issuer
+        run: ./build.sh
+
+      # fails if lockfile is out of date
+      # https://users.rust-lang.org/t/check-if-the-cargo-lock-is-up-to-date-without-building-anything/91048/5
+      # Run only dummy_issuer to avoid building dummy_relying_party
+      - name: Cargo tests
+        run: cargo test --package dummy_issuer