automate releases

Now that otel-cli has a good functional testing story, it's time to finally automate the last bits of the release process to get my computer out of the loop. I believe the remaining steps are something like this:

- create a new token with permissions to write to packages and releases
- set up a new GH Action that fires on new tags
- build the release and run a `go test -v` which will run functional tests to validate the tag
- current tests already do this
- run goreleaser and it will do the rest
- this must depend on a successful functional test

Once this is complete, a release can be made by tagging a sha and pushing tags, so package & release write access can be restricted to actions only.

Start by reviewing the current functional tests and the repository's release configuration, then inspect the GitHub Actions setup and how GoReleaser is invoked. The work is done when tagging a commit runs the functional tests first and, only on success, publishes the package and release without a developer's computer involved.

Written by the indexing model from the issue text.