C#: Replace libnethost dependency to find hostfxr

We want to replace libnethost as it gives us issues with some compilers.
Our implementation tries to mimic libnethost's hostfxr_resolver search
logic. We try to use the same function names for easier comparing in
case we need to update this in the future.

misc/scripts/clang_format.sh

@@ -7,8 +7,8 @@ set -uo pipefail
 
 # Loops through all code files tracked by Git.
 git ls-files -- '*.c' '*.h' '*.cpp' '*.hpp' '*.cc' '*.hh' '*.cxx' '*.m' '*.mm' '*.inc' '*.java' '*.glsl' \
-                ':!:.git/*' ':!:thirdparty/*' ':!:platform/android/java/lib/src/com/google/*' ':!:*-so_wrap.*' \
-                ':!:tests/python_build/*' |
+                ':!:.git/*' ':!:thirdparty/*' ':!:*/thirdparty/*' ':!:platform/android/java/lib/src/com/google/*' \
+                ':!:*-so_wrap.*' ':!:tests/python_build/*' |
 while read -r f; do
     # Run clang-format.
     clang-format --Wno-error=unknown -i "$f"