Add structure around raw and outgoing messages

Raw messages (that is, their YAML definitions) have been moved into
messages/ and their outgoing counterparts (i.e., the JSON blobs) have
been moved into outgoing/

Makefile

@@ -2,10 +2,11 @@ PYTHON = python3
 FLAGS = -c
 CMD = 'import sys, yaml, json; json.dump(yaml.load(sys.stdin, Loader=yaml.Loader), sys.stdout, indent=2)'
 
-all: cfr.json cfr-fxa.json cfr-heartbeat.json whats-new-panel.json \
-	messaging-experiments.json message-groups.json moments.json
+all: outgoing/cfr-fxa.json outgoing/cfr-heartbeat.json outgoing/cfr.json \
+     outgoing/message-groups.json outgoing/messaging-experiments.json \
+     outgoing/moments.json outgoing/whats-new-panel.json
 
-%.json:%.yaml pre-build
+outgoing/%.json: messages/%.yaml pre-build
 	$(PYTHON) $(FLAGS) $(CMD) < $< > $@
 
 .PHONY: clean check
@@ -17,9 +18,9 @@ clean:
 	rm *.json
 
 check:
-	scripts/validate.py cfr cfr.json
-	scripts/validate.py moments-page moments.json
-	scripts/validate.py cfr-fxa cfr-fxa.json
-	scripts/validate.py whats-new-panel whats-new-panel.json
-	scripts/validate.py messaging-experiments messaging-experiments.json
-	scripts/validate.py message-groups message-groups.json
+	scripts/validate.py cfr outgoing/cfr.json
+	scripts/validate.py moments-page outgoing/moments.json
+	scripts/validate.py cfr-fxa outgoing/cfr-fxa.json
+	scripts/validate.py whats-new-panel outgoing/whats-new-panel.json
+	scripts/validate.py messaging-experiments outgoing/messaging-experiments.json
+	scripts/validate.py message-groups outgoing/message-groups.json