tut build should optionally discard git changes from the build process

[sc0ttkclark]

Every time I run tut build, the git repos have lock changes that I don't intend to keep/commit. We should add an option for the tut build command that allows for resetting each plugin git changes to the lock files specifically. Discarding those changes if they have changes.

Files to discard changes for:

• package-lock.json
• package.json (if changed)
• common/package-lock.json (if exists)
• common/package.json (if changed, if exists)

The package.json files change some times, but that's usually because of formatting changes that the build process introduces. Leads should handle those exceptions themselves and it will be self-evident when they run their builds without the discard option.