check_axi_stream non-blocking

[eschmidscs]

This resolves #477

I reused the same function with an additional argument with default value for backward compatibility (compared to the current master).
I prefer that to a separate function, but let me know if you think otherwise.

Only the specific axi_stream stuff is updated. One could think of doing the same to the generic stream_slave, but I can't handle the consequences (would need to update the uart...).

Running all checks in verification_components seems to fail with questa due to some delta-cycle differences with GHDL... :-/ GHDL looks fine here.

[kraigher]

Did the tests fail in questa on master as well? Unfortunately we cannot run CI on the commercial simulators like we do with GHDL.

[eschmidscs]

The test already there, yes. It is the "tb_avalon_master.wait until idle" test in probably all configurations. I did not look into it - it fails with questa but is ok with ghdl.

Then the new testcase "tb_axi_stream.test back-to-back failing check" fails with questa, but not with ghdl. This is related to the setting-up of the logging mock. I played around a bit with the order of the delays and commands. It seems I can make it work with questa easily, but then it fails with ghdl.
I got the feeling that it depends on the scheduling of ready processes in one delta cycle...