run_designs fixes (#1597)

+ Add JSON support to "matrix" mode
~ Rename "regression mode" to "matrix", as it more accurately reflects a combination of variables
~ Replace bizzare "regression script" with a JSON file achieving basically the same thing
~ `run_designs` now clears run paths before it starts
~ `run_designs` no longer attempts to generated reports for runs that fail at startup
~ `verify_versions` no longer attempts to check the PDK if the environment variable PDK is not set
~ `scripts/config/config.py:get_config` -> `get_config_for_run` (more accurate)
~ `scripts/config/tcl.py:read_tcl_env` no longer exits unilaterally, raises an exception normally
- Remove Test #892 
- Remove `Tcl` support from matrix mode: not tenable
- Remove Tcl extraction shell script
---
Resolves #1458

.github/scripts/run_tests.py

@@ -61,6 +61,8 @@ docker_command = [
             "--benchmark",
             os.path.join("regression_results", "benchmark_results", "SW_HD.csv"),
             "--show_output",
+            "--config_file",
+            "config",
             design,
         ]
     ),