Set up imports properly at runtime

[sarahec]

svutRun enables svut_h.sv inclusion by copying it into the source directory and then deleting it after. We could make tests run a bit faster (and pave the way for new test features) by passing this information to the simulator instead.

At the same time, tests that use a split src/test directory structure have to use weird tricks like prefixing all includes with ../src/. This is the kind of information that should be passed as an include option and is one that the tool can detect (i.e. not requiring the user to pass a bunch of arguments on the command line.)

So: Enable the tool to detect and specify a default set of imports (which can then be modified by the command line flags.)

[sarahec]

Closing due to not having the time to pursue