LLDB automatically discovers, but doesn't automatically load, scripts in
the dSYM bundle. This is to prevent running untrusted code. Users can
choose to import the script manually or toggle a global setting to
override this policy. This isn't a great user experience: the former
quickly becomes tedious and the latter leads to decreased security.
This PR offers a middle ground that allows LLDB to automatically load
scripts from trusted dSYM bundles. Trusted here means that the bundle
was signed with a certificate trusted by the system. This can be a
locally created certificate (but not an ad-hoc certificate) or a
certificate from a trusted vendor.