Add .pdkignore to exclude some files from tar ball

We've seen release job failures caused by too large tarball, which
contains irrelevant files like git history.

Let's exclude these files to reduce size of the archive.

The file is copied from the puppetlabs repositories with some files
specific to OpenStack projects added.

Change-Id: Ib2da55f670739f618664bd849daad5fc3c0db62c

.pdkignore

@@ -0,0 +1,51 @@
+# common list used in puppetlabs repos
+.git/
+.*.sw[op]
+.metadata
+.yardoc
+.yardwarns
+*.iml
+/.bundle/
+/.idea/
+/.vagrant/
+/coverage/
+/bin/
+/doc/
+/Gemfile.local
+/Gemfile.lock
+/junit/
+/log/
+/pkg/
+/spec/fixtures/manifests/
+/spec/fixtures/modules/*
+/tmp/
+/vendor/
+/convert_report.txt
+/update_report.txt
+.DS_Store
+.project
+.envrc
+/inventory.yaml
+/spec/fixtures/litmus_inventory.yaml
+/.fixtures.yml
+/Gemfile
+/.gitattributes
+/.gitignore
+/.pdkignore
+/.puppet-lint.rc
+/Rakefile
+/rakelib/
+/.rspec
+/..yml
+/.yardopts
+/spec/
+/.vscode/
+/.sync.yml
+/.devcontainer/
+# OpenStack-specific files
+/bindep.txt
+/.gitreview
+/setup.cfg
+/setup.py
+/tox.ini
+/.zuul.yaml