gifn-apply: add a "reuse" Tox environment to the first stage

We have already prepared the grounds for checking the SPDX
copyright and license tags using the reuse tool; let's invoke it.

Also, actually add the .gitignore file that will help reuse
ignore test artifacts.

Change-Id: Id623c2a2d5d378d1bb427b62b1431d2cbb08a395
3 files changed
tree: 1f1bde1e8bbd7192e02eddd2d7f6c83d4accc7ac
  1. .gitreview
  2. patches/
  3. tools/