In particular, allow a pair of a relative-to directory and a base
directory. Paths that syntactically extend the base directory are
recorded as relative to the relative-to directory (which must
syntactically extend the base directory).
The compilation manager now sets the parameter to a pair with
the base directory as the main collection directory, if the source
file's path extends that directory's path.
This generalization solves problems created by cross-module inlining,
where the source location of a procedure in bytecode can now be in a
different file than the enclosing module's file.
Also add a test that checks whether the build directory shows up
in any ".zo", ".dep", or documentation ".html" files.
Closes PR 12549
