SiFive Internal Release 1.19.0

What's Changed

• [ExportVerilog] Remove old emission code by @uenoku in #4079
• Fixes to build system to support unittests again, add to CI by @dtzSiFive in #4082
• [FSMToSV] Erase typescope if empty by @mortbopet in #4093
• [SV] Add feature flags to new SVExtractTestCode features. by @mikeurbach in #4094

Full Changelog: sifive/1/18/0...sifive/1/19/0