This frees `Class.qll`, `Exprs.qll`, and `Function.qll` from the
clutches of points-to. For the somewhat complicated setup with
`getLiteralObject` (an abstract method), I opted for a slightly ugly but
workable solution of just defining a predicate on `ImmutableLiteral`
that inlines each predicate body, special-cased to the specific instance
to which it applies.
The `**/src_archive/**` exclusion patterns seem to have to do with
trying to exclude archived source files from being picked up for the
extractor while running the test itself. However it seems that directory
is not being used any more by `codeql` (which uses a `src` directory
instead).
A `*.testproj` exclusion pattern will work in a more robust way, by
excluding any file inside the database being built.
I'm beginning to realise why I didn't do the `toString` overriding way
back when. Thankfully, now that all of our tests are in the same place,
this is actually not a terrible ordeal.
