[chore] The Big Middleware and API Refactor (tm) (#1250)

* interim commit: start refactoring middlewares into package under router

* another interim commit, this is becoming a big job

* another fucking massive interim commit

* refactor bookmarks to new style

* ambassador, wiz zeze commits you are spoiling uz

* she compiles, we're getting there

* we're just normal men; we're just innocent men

* apiutil

* whoopsie

* i'm glad noone reads commit msgs haha :blob_sweat:

* use that weirdo go-bytesize library for maxMultipartMemory

* fix media module paths

internal/processing/oauth.go

@@ -22,6 +22,7 @@ import (
 	"net/http"
 
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/oauth2/v4"
 )
 
 func (p *processor) OAuthHandleAuthorizeRequest(w http.ResponseWriter, r *http.Request) gtserror.WithCode {
@@ -33,3 +34,8 @@ func (p *processor) OAuthHandleTokenRequest(r *http.Request) (map[string]interfa
 	// todo: some kind of metrics stuff here
 	return p.oauthServer.HandleTokenRequest(r)
 }
+
+func (p *processor) OAuthValidateBearerToken(r *http.Request) (oauth2.TokenInfo, error) {
+	// todo: some kind of metrics stuff here
+	return p.oauthServer.ValidationBearerToken(r)
+}