Support lazy evaluation of signed module output file

[benmusson]

This change converts .map/.get to .flatMap to allow for lazier evaluation of the signed module output file.

[brianeray]

I think this is implicitly tested by existing coverage in SignModuleTest, but need to loop back around on Monday to be sure.

[brianeray]

OK, finally getting to this today. One thing is that since you are coding in your own master fork it's prone to echoes in the commit history, ie commit 81e986e in the current PR. This needs to be rebased on the upstream inductiveautomation/ignition-module-tools master to remove that from the PR and leave only the commit(s) fixing the issue.

Spinning up another branch in your fork to replace this PR might be easier, but up to you.

Either way I'm kicking the tires on this commit locally. Should be able to wrap up this (or a replacement) PR today. 🤞

[benmusson]

One thing is that since you are coding in your own master fork it's prone to echoes in the commit history, ie commit 81e986e in the current PR.

Yup, that is kinda gross. Will fix today.

[brianeray]

I try to tread lightly on suggestions on cleaning up commit history because I don't know how much expertise any particular contributor has with Git itself. Much of its functionality is not obvious and getting clean commit history can be even less obvious. E.g. when to use merge vs pull vs rebase vs cherry-pick vs whatever. They all smoosh code from two branches together.

[benmusson]

@brianeray Eh, I think it's good to be picky 😉
#55