changed LVS config from shell to json

[marwaneltoukhy]

@d-m-bailey Please take a look, and test it

json config file can be found here: efabless/caravel_user_project#274

[d-m-bailey]

@marwaneltoukhy
A few questions and possible suggestions.

        env_var = w.split("$")[1]
        if env_var in lvs_env:
            if not is_path(value):
                value = value.replace(w, lvs_env.get(env_var))
            else:
                value = os.path.join(os.path.dirname(value), os.path.splitext(value)[0].replace(w, lvs_env.get(env_var)) + os.path.splitext(value)[1])

1. Since w will always be $[A-Za-z_]*, I think env_var = w[1:] might be clearer than w.split("$")[1] although both give the same results. We're not allowing the shell syntax ${var}, correct?

2. Why do you have different replacement logic based on whether value is a path or not?

3. Using a global replace may cause problems for a strings like $PDK/$PDK_ROOT.

                value = value.replace(w, lvs_env.get(env_var))

I recommend limiting the replacement to the first occurrence.

                value = value.replace(w, lvs_env.get(env_var), 1)

It looks like this pull request is removing the option to not run LVS. Maybe not having a lvs_config file would be a sufficient reason not to run LVS and issue a warning? (is that what currently happens?)

[marwaneltoukhy]

It looks like this pull request is removing the option to not run LVS. Maybe not having a lvs_config file would be a sufficient reason not to run LVS and issue a warning? (is that what currently happens?)

We are going to remove the check from the platform, but we agreed that the flag shouldn't be added here, and I created a target in the user project for users who don't want to run LVS as part of precheck. So basically the normal flow locally will run LVS automatically. we're requiring users to have the lvs config, if not the precheck will fail.