Java: Support `CompileTimeConstantExpr` for constant fields from compiled classes

[aschackmull]

Discussed in #8650

^{Originally posted by Marcono1234 April 2, 2022}
When compiled classes have constant fields, source code referencing them uses the constant value. A simple example for this is the following:

class ConstantTest {
    static final int VALUE = Integer.MAX_VALUE;
}

Compiling this class and inspecting it with javap -v shows that the value of Integer.MAX_VALUE, that is 2147483647, has been stored in the class file (instead of performing a field read). This is also explicitly mentioned in JLS 17 §13.4.9.

Currently CodeQL's CompileTimeConstantExpr does not support this; I assume because the information is missing from the database. Would it be possible to store this information in the database during extraction?

[Marcono1234]

Depending on how this is implemented it might be necessary to adjust the documentation of the literal classes because they currently claim that the MinusExpr is modelled separately, which might no longer be the case then, see also #5475 and #8645 (comment).