Remove auth plugins

auth/README.md

auth/basic-auth/.gitignore

auth/basic-auth/Dockerfile

auth/basic-auth/README.md

auth/basic-auth/go.mod

auth/basic-auth/go.sum

auth/basic-auth/main.go

auth/basic-auth/main_test.go

...sic-auth/vendor/github.com/openfaas/faas-provider/LICENSE

...ndor/github.com/openfaas/faas-provider/auth/basic_auth.go

...dor/github.com/openfaas/faas-provider/auth/credentials.go

auth/basic-auth/vendor/github.com/pkg/errors/.gitignore

auth/basic-auth/vendor/github.com/pkg/errors/.travis.yml

auth/basic-auth/vendor/github.com/pkg/errors/LICENSE

auth/basic-auth/vendor/github.com/pkg/errors/Makefile

auth/basic-auth/vendor/github.com/pkg/errors/README.md

auth/basic-auth/vendor/github.com/pkg/errors/appveyor.yml

auth/basic-auth/vendor/github.com/pkg/errors/errors.go

auth/basic-auth/vendor/github.com/pkg/errors/go113.go

auth/basic-auth/vendor/github.com/pkg/errors/stack.go