Move the file public header files to `include` dir (#4636)

* Move the file public header files to `include` dir

Close the issue (#4635).

Move the following headers files to a `include` dir
located at root dir of slang repo:

 slang-com-helper.h -> include/slang-com-helper.h
 slang-com-ptr.h -> include/slang-com-ptr.h
 slang-gfx.h -> include/slang-gfx.h
 slang.h -> include/slang.h

Change cmake/SlangTarget.cmake to add include path to
every target, and change the source file to use
"#include <slang.h>" to include the public headers.

The source code update is by the script like follow:

```
fileNames_slang=$(grep -r "\".*slang\.h\"" source/ -l)

for fileName in "${fileNames_slang[@]}"
do
    echo "$fileName"
    sed -i "s/\".*slang\.h\"/\"slang\.h\"/" $fileName
done
```

* Fix the test issues

* Fix cpu test issues by adding include seach path

* Update cmake to not add include path for every target

Also change "#include <slang.h>" to "include "slang.h" " to
make the coding style consistent with other slang code.

* Change public include to private include for unit-test and slang-glslang

1 files changed, 1 insertions, 1 deletions

diff --git a/tools/test-process/test-process-main.cpp b/tools/test-process/test-process-main.cpp
index 9729c24b7..ea8f30c11 100644
--- a/tools/test-process/test-process-main.cpp
+++ b/tools/test-process/test-process-main.cpp
@@ -5,7 +5,7 @@
 #include <string.h>
 
 
-#include "../../slang-com-helper.h"
+#include "slang-com-helper.h"
 
 #include "../../source/core/slang-string.h"
 #include "../../source/core/slang-io.h"