Remove checked-in go.work, add generation

go.work is not respected by imports, which means that our test
environment - if it uses go.work - will differ from what'll be used by
third parties which import our core module.

This commit adds a generation target for go.work which will allow users
to opt-in to using it locally without it being enabled by default for
everyone.

See golang/go#53502 for discussion on whether
or not go.work should be checked in.

Signed-off-by: Ashley Davis <ashley.davis@jetstack.io>

.gitignore

@@ -19,3 +19,4 @@ _bin/
 user.bazelrc
 *.bak
 /go.work.sum
+**/go.work

make/tools.mk

@@ -467,3 +467,9 @@ tidy:
 	cd cmd/webhook && go mod tidy
 	cd test/integration && go mod tidy
 	cd test/e2e && go mod tidy
+
+.PHONY: go-workspace
+go-workspace:
+	@rm -f go.work
+	go work init
+	go work use . ./cmd/acmesolver ./cmd/cainjector ./cmd/controller ./cmd/ctl ./cmd/webhook ./test/integration ./test/e2e