clang-format improvements (#1251)

* clang-format improvements

- Add a clang-format linter check to the PR pipeline
- Apply clang-format to files where the linter initially failed
- Remove `CommentPragmas` from `.clang-format`
- Remove all `// clang-format off` and `// NO-FORMAT` as they are not needed
- Remove a commented out `GSL_SUPPRESS`

* clang-format 20

* pipeline fail

* Update .github/workflows/clang-format.yml

Co-authored-by: Carson Radtke <nosrac925@gmail.com>

* output used clang-format version

* installed version is 18 which replaces "GSL_SUPPRESS(bounds.1)" with "GSL_SUPPRESS(bounds .1)"

* only include/gsl, not include

to prevent formatting of include/CMakeLists.txt

* apply clang-format[-20]

In a VS2026 developer command prompt I ran `clang-format -i include\gsl\* --assume-filename x.cpp`. This was necessary because VS GUI does not format files without an extension :(. Please note that `--assume-filename` is necessary here, otherwise the files will not be formatted. Surprisingly the behaviour for the formatter differs from the behaviour of `lang-format(-20) --dry-run --Werror include/gsl/*` where clang-format recognizes that the files is C++.

* change "#if 0" back to original version with comments only

* formatting scripts for windows and linux

for linux with linter (shfmt and shellcheck)

* add WhitespaceSensitiveMacros: [GSL_SUPPRESS]

* provide path for clang-format (Windows)

Currently not clear to me:
On my personal computer at home, when I start "Developer Command Prompt for VS18", I can run `clang-format` without providing the path.
On my managed (domain) company computer, when I start "Developer Command Prompt for VS18", I can NOT run `clang-format` without providing the path. I need to call `"%VCINSTALLDIR%Tools\Llvm\bin\clang-format"`.
I have no idea what the difference is. At least the version `"%VCINSTALLDIR%Tools\Llvm\bin\clang-format"` works on both computers, so I add the path.

---------

Co-authored-by: Werner Henze <w.henze@avm.de>
Co-authored-by: Carson Radtke <nosrac925@gmail.com>
Co-authored-by: Werner Henze <werner.henze+gitcommits@posteo.de>

include/gsl/byte

@@ -82,11 +82,13 @@ namespace gsl
 {
 #if GSL_USE_STD_BYTE
 
-namespace impl {
-// impl::byte is used by gsl::as_bytes so our own code does not trigger a deprecation warning as would be the case when we used gsl::byte.
-// Users of GSL should only use gsl::byte, not gsl::impl::byte.
-using byte = std::byte;
-}
+namespace impl
+{
+    // impl::byte is used by gsl::as_bytes so our own code does not trigger a deprecation warning as
+    // would be the case when we used gsl::byte. Users of GSL should only use gsl::byte, not
+    // gsl::impl::byte.
+    using byte = std::byte;
+} // namespace impl
 
 using byte GSL_DEPRECATED("Use std::byte instead.") = std::byte;
 
@@ -100,11 +102,13 @@ enum class byte_may_alias byte : unsigned char
 {
 };
 
-namespace impl {
-// impl::byte is used by gsl::as_bytes so our own code does not trigger a deprecation warning as would be the case when we used gsl::byte.
-// Users of GSL should only use gsl::byte, not gsl::impl::byte.
-using byte = gsl::byte;
-}
+namespace impl
+{
+    // impl::byte is used by gsl::as_bytes so our own code does not trigger a deprecation warning as
+    // would be the case when we used gsl::byte. Users of GSL should only use gsl::byte, not
+    // gsl::impl::byte.
+    using byte = gsl::byte;
+} // namespace impl
 
 template <class IntegerType, std::enable_if_t<std::is_integral<IntegerType>::value, bool> = true>
 constexpr byte& operator<<=(byte& b, IntegerType shift) noexcept
@@ -170,15 +174,13 @@ constexpr IntegerType to_integer(byte b) noexcept
 
 #endif // GSL_USE_STD_BYTE
 
-
 template <typename T>
-// NOTE: need suppression since c++14 does not allow "return {t}"
-// GSL_SUPPRESS(type.4) // NO-FORMAT: attribute // TODO: suppression does not work
 constexpr gsl::impl::byte to_byte(T t) noexcept
 {
-    static_assert(std::is_same<T, unsigned char>::value,
-                  "gsl::to_byte(t) must be provided an unsigned char, otherwise data loss may occur. "
-                  "If you are calling to_byte with an integer constant use: gsl::to_byte<t>() version.");
+    static_assert(
+        std::is_same<T, unsigned char>::value,
+        "gsl::to_byte(t) must be provided an unsigned char, otherwise data loss may occur. "
+        "If you are calling to_byte with an integer constant use: gsl::to_byte<t>() version.");
     return gsl::impl::byte(t);
 }