chore(*) improve go mod handling in 1.14

Having a folder called `vendor` confises go 1.14. Rename it to `vendored`
and this solves many potential issues. Including the need to pass `-mod=mod`
in many cases.

https://github.com/Kong/kuma/pull/718#issuecomment-625894360

Signed-off-by: Nikolay Nikolaev <nikolay.nikolaev@konghq.com>

.dockerignore

@@ -16,4 +16,4 @@ go.sum
 Makefile*
 pkg/*
 !pkg/config/*
-vendor
+vendored

Makefile

@@ -29,7 +29,7 @@ build_info_ld_flags := $(foreach entry,$(build_info_fields), -X github.com/Kong/
 LD_FLAGS := -ldflags="-s -w $(build_info_ld_flags)"
 GOOS := $(shell go env GOOS)
 GOARCH := $(shell go env GOARCH)
-GOFLAGS := -mod=mod
+GOFLAGS :=
 GO_BUILD := GOOS=${GOOS} GOARCH=${GOARCH} CGO_ENABLED=0 go build -v $(GOFLAGS) $(LD_FLAGS)
 GO_RUN := CGO_ENABLED=0 go run $(GOFLAGS) $(LD_FLAGS)
 GO_TEST := go test $(GOFLAGS) $(LD_FLAGS)
@@ -243,7 +243,7 @@ golangci-lint: ## Dev: Runs golangci-lint linter
 	$(GOLANGCI_LINT_DIR)/golangci-lint run -v
 
 imports: ## Dev: Runs goimports in order to organize imports
-	goimports -w -local github.com/Kong/kuma -d `find . -type f -name '*.go' -not -name '*.pb.go' -not -path './vendor/*'`
+	goimports -w -local github.com/Kong/kuma -d `find . -type f -name '*.go' -not -name '*.pb.go' -not -path './vendored/*'`
 
 check: generate fmt vet docs golangci-lint imports tidy ## Dev: Run code checks (go fmt, go vet, ...)
 	make generate manifests -C pkg/plugins/resources/k8s/native

go.mod

@@ -57,7 +57,7 @@ replace (
 	github.com/Kong/kuma/api => ./api
 	github.com/Kong/kuma/pkg/plugins/resources/k8s/native => ./pkg/plugins/resources/k8s/native
 
-	github.com/prometheus/prometheus => ./vendor/github.com/prometheus/prometheus
+	github.com/prometheus/prometheus => ./vendored/github.com/prometheus/prometheus
 	github.com/spiffe/spire/proto/spire => github.com/spiffe/spire/proto/spire v0.10.0
 	gopkg.in/fsnotify.v1 => gopkg.in/fsnotify.v1 v1.4.7
 	k8s.io/client-go => k8s.io/client-go v0.18.2

pkg/plugins/resources/k8s/native/.gitignore

@@ -15,7 +15,7 @@ bin
 
 # Kubernetes Generated files - skip generated files, except for vendored files
 
-!vendor/**/zz_generated.*
+!vendored/**/zz_generated.*
 
 # editor and IDE paraphernalia
 .idea