Make repo compliant

[RaphaelVogel]

What this PR does / why we need it:

• Updated CONTRIBUTING.md file
• Created/Updated LICENSE file
• Created/Updated .reuse/dep5 file
• Created/Updated LICENSES folder
• Added badge for reuse compliance in README.md file and registered repo with REUSE API
• Adapted add_license_headers.sh script to use correct license and added file license_boilerplate.txt
• License/Copyright header replacement for 'non-go' files
  • .ci/test
  • .ci/local_integration_test
  • .ci/build
  • .ci/check
  • hack/add_license_headers.sh
  • hack/tools.mk
• License/Copyright header replacement for 'go' files
  • test/integration/provider/azure.go
  • test/integration/provider/rti.go
  • test/integration/controller/controller_test.go
  • test/integration/controller/controller_suite_test.go
  • pkg/azure/testhelp/constants.go
  • pkg/azure/testhelp/providerspec.go
  • pkg/azure/testhelp/errors.go
  • pkg/azure/testhelp/fakes/behavior.go
  • pkg/azure/testhelp/fakes/resourcegroupaccess.go
  • pkg/azure/testhelp/fakes/marketplaceagreementaccess.go
  • pkg/azure/testhelp/fakes/factory.go
  • pkg/azure/testhelp/fakes/subnetaccess.go
  • pkg/azure/testhelp/fakes/nicaccess.go
  • pkg/azure/testhelp/fakes/clusterstate.go
  • pkg/azure/testhelp/fakes/diskaccess.go
  • pkg/azure/testhelp/fakes/resourcegraphaccess.go
  • pkg/azure/testhelp/fakes/util.go
  • pkg/azure/testhelp/fakes/imageaccess.go
  • pkg/azure/testhelp/fakes/vmaccess.go
  • pkg/azure/testhelp/fakes/machineresources.go
  • pkg/azure/access/factory.go
  • pkg/azure/access/types.go
  • pkg/azure/access/errors/errors.go
  • pkg/azure/access/helpers/subnet.go
  • pkg/azure/access/helpers/disk.go
  • pkg/azure/access/helpers/resourcegraph.go
  • pkg/azure/access/helpers/vm.go
  • pkg/azure/access/helpers/resourcegroup.go
  • pkg/azure/access/helpers/marketplaceagreement.go
  • pkg/azure/access/helpers/vmimage.go
  • pkg/azure/access/helpers/nic.go
  • pkg/azure/instrument/instrument.go
  • pkg/azure/provider/provider.go
  • pkg/azure/provider/provider_test.go
  • pkg/azure/provider/helpers/secret.go
  • pkg/azure/provider/helpers/machineclass_test.go
  • pkg/azure/provider/helpers/machineclass.go
  • pkg/azure/provider/helpers/driver.go
  • pkg/azure/provider/helpers/driver_test.go
  • pkg/azure/utils/concurrent.go
  • pkg/azure/utils/tags.go
  • pkg/azure/utils/checks.go
  • pkg/azure/utils/concurrent_test.go
  • pkg/azure/utils/checks_test.go
  • pkg/azure/utils/names.go
  • pkg/azure/api/validation/validation_test.go
  • pkg/azure/instrument/instrument_test.go
  • pkg/azure/provider/helpers/resourcegraphprocessor.go
  • pkg/azure/utils/names_test.go
  • pkg/azure/utils/resourcetype.go
  • pkg/azure/utils/vm.go

Additional information To keep this repository compliant, CODEOWNERS must maintain their third party dependencies in the vendor folder using .reuse/dep5 file. To prevent constant maintenance effort, it is highly recommended to remove the vendor folder. In this case no third party dependencies of the vendor folder must be maintained anymore!