Move clog out of the repo (cosmos#4249)

Following up cosmos#4225:

- Move clog into an external repository
- Update devtools Makefile.
- Add .clog.yaml file required by clog's latest version.

Closes: cosmos#4222

.clog.yaml

@@ -0,0 +1,12 @@
+sections:
+  breaking: Breaking Changes
+  features: Features
+  improvements: Improvements
+  bugfixes: Bugfixes
+
+tags:
+  - gaia
+  - gaiacli
+  - gaiarest
+  - sdk
+  - tendermint

contrib/devtools/Makefile

@@ -66,8 +66,8 @@ $(GOIMPORTS):
 $(GOSUM): ./contrib/devtools/gosum/main.go
 	go install -mod=readonly ./$(<D)/
 
-$(CLOG): ./contrib/devtools/clog/main.go
-	go install -mod=readonly ./$(<D)/
+$(CLOG):
+	$(call go_install,alessio,clog,1)
 
 tools-clean:
 	rm -f $(GOLANGCI_LINT) $(STATIK) $(GOIMPORTS) $(GOSUM) $(CLOG)