build: add fietsje config and alias for Delve debugger

Test Plan: Debugged a running process using `bazel run :dlv`.

X-Origin-Diff: phab/D550
GitOrigin-RevId: 3bea727afc0cc275fac19238067d871c42beef19
diff --git a/build/fietsje/main.go b/build/fietsje/main.go
index 7aa020b..875d5f7 100644
--- a/build/fietsje/main.go
+++ b/build/fietsje/main.go
@@ -96,6 +96,9 @@
 	// used by deltagen
 	p.collectOverride("github.com/lyft/protoc-gen-star", "v0.4.14")
 
+	// for interactive debugging during development (//:dlv alias)
+	depsDelve(p)
+
 	// First generate the repositories starlark rule into memory. This is because rendering will lock all unlocked
 	// dependencies, which might take a while. If a use were to interrupt it now, they would end up with an incomplete
 	// repositories.bzl and would have to restore from git.