feat(integrations): add first simple npm integration

Integrations are simple helpers to make integration with existing tools easier.
At basic npm support, the integration will set the version before release to the `package.json`

```yml
integrations:
  npm:
    enabled: true
```

Makefile

@@ -0,0 +1,14 @@
+
+
+all: build
+
+.PHONY: build
+
+build:
+	go build -o build/go-semantic-release-temp ./cmd/go-semantic-release/
+
+lint:
+	golangci-lint run --print-issued-lines=false --fix ./...
+
+test:
+	go test --coverprofile coverage.out -v -race -parallel 20 ./...