Overwork project infrastructure (#5218)

* 📝 overwork project infrastructure

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 fix GCC16 issue

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 fix GCC16 issue

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 only build module for GCC

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 🐛 fix build

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 📝 fix documentation

Closes #5012: fix the error_handler_t::ignore wording

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* 📝 fix documentation

Closes #4354: fix "Custom data source" example

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/windows.yml

@@ -25,6 +25,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          persist-credentials: false
       - name: Set up MinGW
         uses: egor-tensin/setup-mingw@41b837e47d7f85214629d255b9c4bc3fcbe9fd63 # v3.0
         with:
@@ -48,6 +50,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          persist-credentials: false
       - name: Set extra CXX_FLAGS for latest std_version
         id: cxxflags
         run: |
@@ -78,6 +82,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          persist-credentials: false
       - name: Install Clang
         run: curl -fsSL -o LLVM${{ matrix.version }}.exe https://github.com/llvm/llvm-project/releases/download/llvmorg-${{ matrix.version }}/LLVM-${{ matrix.version }}-win64.exe ; 7z x LLVM${{ matrix.version }}.exe -y -o"C:/Program Files/LLVM"
       - name: Set up MinGW
@@ -106,6 +112,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          persist-credentials: false
       - name: Run CMake
         run: cmake -S . -B build -G "Visual Studio 17 2022" -A ${{ matrix.architecture }} -T ClangCL -DJSON_BuildTests=On
       - name: Build
@@ -117,6 +125,15 @@ jobs:
     runs-on: windows-2022
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          persist-credentials: false
+      # The module test uses `import std;`, which needs CMake's experimental
+      # import-std support. Its opt-in token is CMake-version-specific, so pin
+      # CMake to the version whose token is set in tests/module_cpp20/CMakeLists.txt.
+      - name: Get pinned CMake and ninja
+        uses: lukka/get-cmake@f5b8fbb4d77cec1acc5a5f9f0df4beffaf5d98d9 # v4.3.4
+        with:
+          cmakeVersion: 4.3.4
       - name: Run CMake (Debug)
         run: cmake -S . -B build -G "Visual Studio 17 2022" -DJSON_CI=ON -DCMAKE_CXX_FLAGS="/permissive- /std:c++latest /utf-8 /W4 /WX"
       - name: Build