Build LLVM for Windows (#248)

This PR changes the CI build scripts to also build LLVM for windows.
**It doesn't build `revive` itself for windows**. This will come in a
follow up. But once we have a LLVM binary release the turn around time
will be much quicker for experimenting with the revive windows build.

I manually uploaded the release those changes produce
[here](https://github.com/paritytech/revive-alex-workflowtest/releases/tag/llvm-18.1.8-revive.22f3ceb).
This enables this PR's CI to find the proper release. This is necessary
because I am also making changes to the folder structure and artifact
naming that the other CI jobs are depending on.

Releases generated from this branch can be inspected here:
https://github.com/paritytech/revive-alex-workflowtest/releases/tag/v0.1.0-dev.12

Summary of changes:
- Change `llvm-builder` to use MSVC toolchain on windows
- Fix `llvm-builder` to work with `.exe` files
- Unify the llvm release jobs into a single one. This removed a lot of
copy pasted code and also speeds up the build by giving each their own
runner.
- Use the LLVM target triple to name the binary releases instead of an
ad-hoc naming convention
- Remove the nested folder hierarchy inside the llvm release. Its just
now a single folder `llvm-<target>` that contains the toolchain.
- Give jobs and workflows consistent names
- Replace all runners bei their `*-latest` counterpart
- Only use `parity-large` to build llvm now. All other jobs use github
runners

.github/workflows/test.yml

@@ -0,0 +1,59 @@
+name: Test
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+    branches: ["main"]
+    types: [opened, synchronize]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  test:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          # without this it will override our rust flags
+          rustflags: ""
+
+      - name: Install Solc
+        uses: ./.github/actions/get-solc
+
+      - name: Download LLVM
+        uses: ./.github/actions/get-llvm
+        with:
+          target: x86_64-unknown-linux-gnu
+
+      - name: Set LLVM Environment Variables
+        run: |
+          echo "LLVM_SYS_181_PREFIX=$(pwd)/llvm-x86_64-unknown-linux-gnu" >> $GITHUB_ENV
+
+      - name: Install Geth
+        run: |
+          sudo add-apt-repository -y ppa:ethereum/ethereum
+          sudo apt update
+          sudo apt install -y ethereum
+
+      # Disabled for now (always install the latest version despite setting it):
+      # https://github.com/bnjbvr/cargo-machete/issues/156
+      #- name: Machete
+      #  uses: bnjbvr/cargo-machete@v0.7.0
+
+      - name: Format
+        run: make format
+
+      - name: Clippy
+        run: make clippy
+
+      - name: Test cargo workspace
+        run: make test-workspace
+
+      - name: Test CLI
+        run: make test-cli