Separate the stop policies from the compile policies completely

Currently, javac has 5 compile policies (enum class CompilePolicy): ATTR_ONLY, CHECK_ONLY, SIMPLE, BY_FILE, BY_TODO.

But actually, the ATTR_ONLY and CHECK_ONLY are stop policies instead of compile policies. They were placed in `CompilePolicy` because of historical reason.

After the options `should-stop.at`, `should-stop.ifError` and `should-stop.ifNoError` being used, we don't need `ATTR_ONLY`, `CHECK_ONLY` any more.

Now, it is good to remove them and separate the stop policies from the compile policies completely.

Note: some places where they are used should be revised, too.

The original thread:
https://mail.openjdk.java.net/pipermail/compiler-dev/2021-May/016759.html