Add 3rd-party LICENSE files to Docker Image distribution

[jsuereth]

Is your feature request related to a problem? Please describe.
Many OSS licenses require re-distribution with said license. E.g. the MIT licenses explicitly states:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

Describe the solution you'd like
We create a licenses/ directory in the relevant distributed DOCKER files that contains all 3p licenses.

Ideally the following would work:

docker create --name="tmp_collector" otel/opentelemetry-collector
docker export tmp_collector | tar -x licenses
docker rm tmp_collector
cat licenses/*

(Note: I can submit a PR).

Describe alternatives you've considered
I didn't consider other alternatives to distributing the license. I guess you could encode it in the binary and dump it in logs at startup?

[jsuereth]

There are two tools I think could be really helpful here:

1. Pivotal's license finder
   • It allows you to opt-in to copy-left license and approve/disallow any the community is uncomfortable with
   • It's highly configurable / flexible
   • It drops an "authorization" report on what decisions were made
   • Available as a docker image
2. Google's go license finder

• Dead simple
• Encodes google's notions of allowable licenses (we can ignore that feature)

[punya]

Is it worth broadening this issue to include tooling that collector distributions (i.e. bundling some set of out-of-tree plugins) can use to generate and bundle a valid LICENSE file?

[jrcamp]

@alolita

[jpkrohling]

As mentioned in the PR, this would be a great fit for the builder.