tests/kernel/interrupt: Add a simple dynamic interrupt test

Platforms which use the GEN_SW_ISR mechanism for interrupt handling
can make use of a really simple whitebox trick for verifying that it
worked (i.e. that the pointer and argument get placed in the table
correctly).

Easy and simple way to get some coverage for dynamic IRQs, which is
currently entirely missing.  Long term we'll want to replace this with
a test that uses the API directly and chooses an arch-specific vector
to set, and triggers it using arch-specific code, but that's quite a
bit more effort and for now we need to land patches to
z_irq_connect_dynamic() which show test coverage.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>