Remove vendored omniauth-azure-oauth2

.gitlab/ci/vendored-gems.gitlab-ci.yml

Gemfile

Gemfile.lock

doc/integration/omniauth.md

lib/gitlab/auth/o_auth/provider.rb

lib/omni_auth/strategies/azure_oauth2.rb

vendor/gems/omniauth-azure-oauth2/.gitlab-ci.yml

vendor/gems/omniauth-azure-oauth2/CHANGELOG.md

vendor/gems/omniauth-azure-oauth2/Gemfile

vendor/gems/omniauth-azure-oauth2/Gemfile.lock

vendor/gems/omniauth-azure-oauth2/LICENSE

vendor/gems/omniauth-azure-oauth2/README.md

vendor/gems/omniauth-azure-oauth2/Rakefile

vendor/gems/omniauth-azure-oauth2/examples/sinatra.rb

...r/gems/omniauth-azure-oauth2/lib/omniauth-azure-oauth2.rb

...r/gems/omniauth-azure-oauth2/lib/omniauth/azure_oauth2.rb

...mniauth-azure-oauth2/lib/omniauth/azure_oauth2/version.rb

...auth-azure-oauth2/lib/omniauth/strategies/azure_oauth2.rb

.../gems/omniauth-azure-oauth2/omniauth-azure-oauth2.gemspec

...zure-oauth2/spec/omniauth/strategies/azure_oauth2_spec.rb