feat: Generate OpenAPI command (sourcenetwork#2235)

## Relevant issue(s)

Resolves sourcenetwork#2234

## Description

This PR adds a command to output the current OpenAPI specification

## Tasks

- [x] I made sure the code is well commented, particularly
hard-to-understand areas.
- [x] I made sure the repository-held documentation is changed
accordingly.
- [x] I made sure the pull request title adheres to the conventional
commit style (the subset used in the project can be found in
[tools/configs/chglog/config.yml](tools/configs/chglog/config.yml)).
- [x] I made sure to discuss its limitations such as threats to
validity, vulnerability to mistake and misuse, robustness to
invalidation of assumptions, resource requirements, ...

## How has this been tested?

`go run ./cmd/genopenapi`

Specify the platform(s) on which this was tested:
- MacOS

cmd/genopenapi/main.go

@@ -0,0 +1,33 @@
+// Copyright 2024 Democratized Data Foundation
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+/*
+genopenapi is a tool to generate and print an OpenAPI specification.
+*/
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/sourcenetwork/defradb/http"
+)
+
+func main() {
+	router, err := http.NewApiRouter()
+	if err != nil {
+		panic(err)
+	}
+	json, err := router.OpenAPI().MarshalJSON()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Fprint(os.Stdout, string(json))
+}

http/handler.go

@@ -29,15 +29,7 @@ var Version string = "v0"
 // playgroundHandler is set when building with the playground build tag
 var playgroundHandler http.Handler = http.HandlerFunc(http.NotFound)
 
-type Handler struct {
-	db  client.DB
-	mux *chi.Mux
-	txs *sync.Map
-}
-
-func NewHandler(db client.DB, opts ServerOptions) (*Handler, error) {
-	txs := &sync.Map{}
-
+func NewApiRouter() (*Router, error) {
 	tx_handler := &txHandler{}
 	store_handler := &storeHandler{}
 	collection_handler := &collectionHandler{}
@@ -50,12 +42,6 @@ func NewHandler(db client.DB, opts ServerOptions) (*Handler, error) {
 		return nil, err
 	}
 
-	router.AddMiddleware(
-		ApiMiddleware(db, txs, opts),
-		TransactionMiddleware,
-		StoreMiddleware,
-	)
-
 	tx_handler.bindRoutes(router)
 	store_handler.bindRoutes(router)
 	p2p_handler.bindRoutes(router)
@@ -74,14 +60,36 @@ func NewHandler(db client.DB, opts ServerOptions) (*Handler, error) {
 	if err := router.Validate(context.Background()); err != nil {
 		return nil, err
 	}
+	return router, nil
+}
+
+type Handler struct {
+	db  client.DB
+	mux *chi.Mux
+	txs *sync.Map
+}
+
+func NewHandler(db client.DB, opts ServerOptions) (*Handler, error) {
+	router, err := NewApiRouter()
+	if err != nil {
+		return nil, err
+	}
+	txs := &sync.Map{}
 
 	mux := chi.NewMux()
 	mux.Use(
 		middleware.RequestLogger(&logFormatter{}),
 		middleware.Recoverer,
 		CorsMiddleware(opts),
 	)
-	mux.Mount("/api/"+Version, router)
+	mux.Route("/api/"+Version, func(r chi.Router) {
+		r.Use(
+			ApiMiddleware(db, txs, opts),
+			TransactionMiddleware,
+			StoreMiddleware,
+		)
+		r.Handle("/*", router)
+	})
 	mux.Get("/openapi.json", func(rw http.ResponseWriter, req *http.Request) {
 		responseJSON(rw, http.StatusOK, router.OpenAPI())
 	})