Bump urfave/cli to v2

[yorinasub17]

This bumps urfave/cli to v2 track. This is an opportunistic upgrade (we're not using any of the features yet) so that we can stay up to date as bugs are fixed.

[brikis98]

I like the idea of updating, but there are quite a few backwards incompatible changes: https://github.com/urfave/cli/blob/master/docs/migrate-v1-to-v2.md. That means that the next time we update any of our CLI apps tot he latest version of gruntwork-cil, we'll have to change a good amount of code and some aspects of the CLI UX will change too (e.g., args vs options order). Is that worth taking on right now?

[yorinasub17]

Is that worth taking on right now?

We don't really have to take on migrating right now (after all, we could just hold the version back in each respective CLI). I thought it would be nice to do this though so that new CLIs will be on the v2 version.

[yorinasub17]

args vs options order

I believe most of our commands/CLI that we have that use this will not be sensitive to this. But I could be wrong.

[brikis98]

I leave this one up to you Yori. If this is not likely to be a painful / yak shave upgrade, then let's stay up to date. If this looks like a lot of potential churn, then perhaps we punt until later.

[osulli]

@yorinasub17 what do you feel your next step will be?

I'm on the fence of using entrypoint for my own Terraform CLI wrapper as it is still using urfave/cli/v1 as opposed to v2.

E: Using this branch

# go.mod
require (
	github.com/gruntwork-io/gruntwork-cli v0.7.1-0.20200831164626-978768fef544 // https://github.com/gruntwork-io/gruntwork-cli/pull/33
)

[yorinasub17]

UPDATE: rebased on master.

[infraredgirl]

We are looking to upgrade the Patcher CLI to v2 of urfave/cli, and it seems this PR needs to get merged first. @yorinasub17 can I help push this over the line? Is only rebasing and fixing conflicts needed or something else as well? Happy to take over this PR and shepherd it to completion!

[yorinasub17]

Just rebased on master and it looks like build passed and no more merge conflict, so this is ready for merge again! (provided you don't find anything else that needs updating).

[infraredgirl]

LGTM!

[yorinasub17]

Thanks for review! Merging now.

[yorinasub17]

Released as https://github.com/gruntwork-io/go-commons/releases/tag/v0.11.0