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/actions/get-solc/action.yml

@@ -0,0 +1,31 @@
+name: "Install Solidity Compiler"
+
+runs:
+  using: "composite"
+  steps:
+    - name: Put Solc Direcotry into PATH
+      shell: bash
+      run: |
+        mkdir -p solc
+        echo "$(pwd)/solc/" >> $GITHUB_PATH
+
+    - name: Figure out Solc Download URL
+      shell: bash
+      run: |
+        if [[ "${{ runner.os }}" == "Linux" ]]; then
+          echo "SOLC_NAME=solc-static-linux" >> $GITHUB_ENV
+        elif [[ "${{ runner.os }}" == "Windows" ]]; then
+          echo "SOLC_NAME=solc-windows.exe" >> $GITHUB_ENV
+        else
+          echo "SOLC_NAME=solc-macos" >> $GITHUB_ENV
+        fi
+
+    - name: Download Solc
+      shell: bash
+      run: |
+        curl -sSL --output solc/solc https://github.com/ethereum/solidity/releases/download/v0.8.28/${SOLC_NAME}
+
+    - name: Make Solc Executable
+      shell: bash
+      run: |
+        chmod +x solc/solc