chore: make contribs/ Makefile dynamic (#2318)

Continues #2013

> People should focus on their contributions in the `contribs/MYFOLDER`
without updating a shared `Makefile` + `.github/contribs/*.yml`.

The CI part has been completed in #2040.
This pull request handles the Makefile portion.

---------

Signed-off-by: moul <94029+moul@users.noreply.github.com>

contribs/Makefile

@@ -3,7 +3,7 @@ help:
 	@echo "Available make commands:"
 	@cat Makefile | grep '^[a-z][^:]*:' | cut -d: -f1 | sort | sed 's/^/  /'
 
-programs=gnodev gnofaucet
+programs=$(wildcard */)
 
 # command to run dependency utilities, like goimports.
 rundep=go run -modfile ../misc/devdeps/go.mod

contribs/gnofaucet/Makefile

@@ -5,3 +5,9 @@ install:
 .PHONY: build
 build:
 	go build -o build/gnofaucet .
+
+test:
+	@echo "XXX: add tests"
+
+lint:
+	@echo "XXX: add lint"

contribs/gnokeykc/Makefile

@@ -0,0 +1,8 @@
+install:
+	go install .
+
+test:
+	@echo "XXX: add tests"
+
+lint:
+	@echo "XXX: add lint"

contribs/gnomd/Makefile

@@ -0,0 +1,8 @@
+install:
+	go install .
+
+test:
+	@echo "XXX: add tests"
+
+lint:
+	@echo "XXX: add lint"