idea.sh missing .exe suffix when invoking javac on WSL

At the end, idea.sh tries to invoke javac, but when running on WSL this results in the following error:

    bin/idea.sh: line 249: /mnt/c/progra~1/java/jdk-16/bin/javac: No such file or directory

Adding a .exe suffix to the javac path fixes this issue, which can be done just for WSL.