SI-7582 ClassfileParser: populate privateWithin of Java module class

The `privateWithin` attribute of Java companion module classes was
correctly set under joint compilation (ie, when using JavaParser),
but not under separate compilation.

This commit remedies this. The test covers variety of Java symbols.
SI-7582 Only inline accessible calls to package-private Java code

Two problems here.

The inliner was using `isPrivate` / `isProtected` to determine access.
The fallthrough considered things to be (bytecode) public. This is okay
in practice for Scala code, which never emits package private code.

Secondly, we must check accessibility of the called symbol *and* its
owner. This case is tested in `run/t7582b`.

This commit tightens the check for Java defined symbols: a) check the owner,
and b) don't assume that `! isPrivate` is accessible.
Merge pull request #2660 from retronym/ticket/7582

SI-7582 Only inline accessible calls to package-private Java code