[systemverilog plugin] Added commands to match read_verilog (systemverilog_defaults,systemverilog_defines)

[tinylabs]

Added commands to match stock verilog frontend in yosys. These will make it easier to utilize higher level tools such as edalize.

[rkapuscik]

Thanks for working on this! Would you please add a simple test for those commands as well?

[alaindargelas]

@tgorochowik @rkapuscik can you merge this in? This is preventing Black-Parrot debugging. Please forget the unit tests, this is simple code. Now this PR is conflicting because it aged.

[mglb]

@alaindargelas just FYI: black-parrot can be debugged without it.

Instead of adding default arguments using systemverilog_defaults -add:

systemverilog_defaults -add -sverilog
systemverilog_defaults -add -Iblack-parrot/external/basejump_stl/bsg_cache
systemverilog_defaults -add -Iblack-parrot/external/basejump_stl/bsg_dataflow
systemverilog_defaults -add (...)

read_systemverilog -defer   black-parrot/external/basejump_stl/bsg_misc/bsg_defines.v
read_systemverilog -defer   black-parrot/external/basejump_stl/bsg_cache/bsg_cache_pkg.v
read_systemverilog -defer   black-parrot/external/basejump_stl/bsg_noc/bsg_noc_pkg.v
(...)

Put all those arguments in every read_systemverilog:

read_systemverilog -defer  -sverilog -Iblack-parrot/external/basejump_stl/bsg_cache -Iblack-parrot/external/basejump_stl/bsg_dataflow (...)  black-parrot/external/basejump_stl/bsg_misc/bsg_defines.v
read_systemverilog -defer  -sverilog -Iblack-parrot/external/basejump_stl/bsg_cache -Iblack-parrot/external/basejump_stl/bsg_dataflow (...)  black-parrot/external/basejump_stl/bsg_cache/bsg_cache_pkg.v
read_systemverilog -defer  -sverilog -Iblack-parrot/external/basejump_stl/bsg_cache -Iblack-parrot/external/basejump_stl/bsg_dataflow (...)  black-parrot/external/basejump_stl/bsg_noc/bsg_noc_pkg.v
(...)

[rkapuscik]

Since this was created from another fork, I created https://github.com/chipsalliance/yosys-f4pga-plugins/pull/417 with a cleaned up and rebased version.