[dv] Configure dvsim to run tests with mask ROM

This commit:

1. Adds configuration options to the dvsim test running
   environment that can be used to select whether a chip-level test (run
   out of flash) is launched with the test ROM or mask ROM.

2. Renames the dvsim run mode for all chip-level tests run with the
   rest ROM has been from `sw_test_mode` --> `sw_test_mode_test_rom`.

3. Checks-in the Cargo.lock file for the ROM_EXT image signer tool
   (since it is a complete binary), in order to enable reproducible
   builds, which is necessary to run this tool on internet-isolated
   simulation infrastructure.

Signed-off-by: Timothy Trippel <ttrippel@google.com>

.gitignore

diff --git a/.gitignore b/.gitignore
index dfb27aa..c8a177d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -62,6 +62,10 @@
 # Rust Cargo build system files.
 Cargo.lock
 sw/host/**/target
+# We check this in to ensure the signing tool is built in a reproducible way
+# under meson, however, once the signing tool is integrated into opentitantool,
+# which is built with Bazel, this can be removed. See lowrisc/opentitan#10465.
+!sw/host/rom_ext_image_tools/signer/Cargo.lock
 
 # Bazel-related cache and output directories
 bazel-*