.pmtignore: implement module layout specification

puppetlabs/puppet-specifications#157 defines
which files are allowed in a puppet module release. This commit
basically changes the .pmtignore into an allowlist, not a denylist
anymore.

moduleroot/.pmtignore.erb

@@ -1,43 +1,21 @@
 # Managed by modulesync - DO NOT EDIT
 # https://voxpupuli.org/docs/updating-files-managed-with-modulesync/
 
-/docs/
-/pkg/
-/Gemfile
-/Gemfile.lock
-/Gemfile.local
-/vendor/
-/.vendor/
-/spec/
-/Rakefile
-/.vagrant/
-/.bundle/
-/.ruby-version
-/coverage/
-/log/
-/.idea/
-/.dependencies/
-/.github/
-/.librarian/
-/Puppetfile.lock
-*.iml
-/.editorconfig
-/.fixtures.yml
-/.gitignore
-/.msync.yml
-/.overcommit.yml
-/.pmtignore
-/.rspec
-/.rspec_parallel
-/.rubocop.yml
-/.sync.yml
-.*.sw?
-/.yardoc/
-/.yardopts
-/Dockerfile
-/HISTORY.md
-<% if ! @configs['paths'].nil? -%>
-<% @configs['paths'].each do |path| -%>
-<%= path %>
-<% end -%>
-<% end -%>
+*
+!/manifests
+!/README*
+!/metadata.json
+!/LICENSE
+!/hiera.yaml
+!/data
+!/templates
+!/files
+!/CHANGELOG*
+!/docs
+!/REFERENCE.md
+!/locales
+!/scripts
+!/tasks
+!/plans
+!/types
+!/bolt_plugin.json