[dvsim] Support for running pre-built SW tests

This PR adds support for running pre-built SW tests, with a few
optimizations:
- Removed `sw_dir` var from hjson - paths to SW tests relative to
`REPO_TOP` are to be indicated now with `sw_test` instead
- Renamed `sw_name` with `sw_test` instead
- Added `sw_test_is_prebuilt` flag to indicate that it is prebuilt
- Supporting updates in `sim.mk` to decide what to do based on the
above flag

Signed-off-by: Srikrishna Iyer <sriyer@google.com>
diff --git a/util/dvsim/SimCfg.py b/util/dvsim/SimCfg.py
index 1afa573..fe94210 100644
--- a/util/dvsim/SimCfg.py
+++ b/util/dvsim/SimCfg.py
@@ -124,7 +124,7 @@
         # TODO: Find a way to set these in sim cfg instead
         ignored_wildcards = [
             "build_mode", "index", "test", "seed", "uvm_test", "uvm_test_seq",
-            "cov_db_dirs", "sw_dir", "sw_name", "sw_build_device"
+            "cov_db_dirs", "sw_test", "sw_test_is_prebuilt", "sw_build_device"
         ]
         self.__dict__ = find_and_substitute_wildcards(self.__dict__,
                                                       self.__dict__,