Yosys read_slang: pass file paths unquoted; give only DUT files with --top and -G

Yosys's read_slang (sv-elab, in OSS CAD Suite) passes its arguments straight to slang, so read_slang "/path/x.sv" fails with 'No such file' because the quotes become part of the name. Use bare paths, and fall back to read_verilog -sv when a path has spaces. Testbench files in the same read_slang call break elaboration ($fsdb tasks, a tb used as a value). Pass only the DUT and package files with --top <module> and -G name=value for the instance's parameters; overriding a localparam with its own elaborated value does no harm. 'help read_slang' prints 'No such command' and exits 0 when the command is missing, and -q hides the help text, so probe without -q and grep for 'read_slang [options]'.