MueLu: Add clang-format workflow and run it on MueLu

.github/workflows/muelu_clang_format.yml

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+name: Check MueLu clang-format
+
+on: [pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - uses: DoozyX/[email protected]
+      with:
+        source: './packages/muelu'
+        exclude: ''
+        extensions: 'cpp,hpp'
+        clangFormatVersion: 14
+        inplace: true
+    - run: git diff HEAD > format_patch.txt
+    - run: if [ "$(cat format_patch.txt)" == "" ] ; then rm format_patch.txt ; fi
+    - uses: actions/upload-artifact@v3
+      if: ${{ hashFiles('format_patch.txt') != '' }}
+      with:
+        name: MueLu format patch
+        path: format_patch.txt
+    - uses: actions/github-script@v3
+      if: ${{ hashFiles('format_patch.txt') != '' }}
+      with:
+        script: |
+          core.setFailed('Please download and apply the formatting patch! It is located at the bottom of the summary tab for this workflow.')

packages/muelu/.clang-format

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+#Official Tool: clang-format version 14.0.0
+#Kokkos options
+BasedOnStyle: google
+SortIncludes: false
+AlignConsecutiveAssignments: true
+AllowShortCaseLabelsOnASingleLine: true
+AllowShortIfStatementsOnASingleLine: true
+#MueLu-specific options
+ColumnLimit: 0
+BreakConstructorInitializersBeforeComma: true
+BreakConstructorInitializers: BeforeComma
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 2