refactor: rename session.sid to session.id

BREAKING CHANGE: The session field `sid` has been renamed to `id` to stay consistent with other APIs which also use `id` terminology to clarify identifiers. The payload of, for example, `/session/whoami` has changed as follows:

```patch
  {
-   "sid": "abcde",
+   "id": "abcde",
    "expires_at": "..."
    "identity": {
      // ..
    }
  }
```

continuity/manager_cookie.go

@@ -97,7 +97,7 @@ func (m *ManagerCookie) sid(ctx context.Context, r *http.Request, name string) (
 	if s, err := x.SessionGetString(r, m.d.CookieManager(), cookieName, name); err != nil {
 		return sid, errors.WithStack(ErrNotResumable.WithDebugf("%+v", err))
 	} else if sid = x.ParseUUID(s); sid == uuid.Nil {
-		return sid, errors.WithStack(ErrNotResumable.WithDebug("sid is not a valid uuid"))
+		return sid, errors.WithStack(ErrNotResumable.WithDebug("session id is not a valid uuid"))
 	}
 
 	return sid, nil

selfservice/strategy/oidc/strategy_test.go

@@ -402,7 +402,7 @@ func TestStrategy(t *testing.T) {
 		require.NoError(t, reg.LoginFlowPersister().ForceLoginFlow(context.Background(), r2.ID))
 		res2, body2 := mrj(t, "valid", afv(t, r2.ID, "valid"), fv, jar)
 		ai(t, res2, body2)
-		assert.NotEqual(t, gjson.GetBytes(body1, "sid"), gjson.GetBytes(body2, "sid"))
+		assert.NotEqual(t, gjson.GetBytes(body1, "id"), gjson.GetBytes(body2, "id"))
 		authAt1, err := time.Parse(time.RFC3339, gjson.GetBytes(body1, "authenticated_at").String())
 		require.NoError(t, err)
 		authAt2, err := time.Parse(time.RFC3339, gjson.GetBytes(body2, "authenticated_at").String())

selfservice/strategy/password/login_test.go

@@ -640,7 +640,7 @@ func TestCompleteLogin(t *testing.T) {
 
 		require.Contains(t, res.Request.URL.Path, "return-ts", "%s", res.Request.URL.String())
 		assert.Equal(t, identifier, gjson.GetBytes(body2, "identity.traits.subject").String(), "%s", body2)
-		assert.NotEqual(t, gjson.GetBytes(body1, "sid").String(), gjson.GetBytes(body2, "sid").String(), "%s\n\n%s\n", body1, body2)
+		assert.NotEqual(t, gjson.GetBytes(body1, "id").String(), gjson.GetBytes(body2, "id").String(), "%s\n\n%s\n", body1, body2)
 	})
 
 	t.Run("should be the same session without forced flag", func(t *testing.T) {
@@ -660,6 +660,6 @@ func TestCompleteLogin(t *testing.T) {
 
 		require.Contains(t, res.Request.URL.Path, "return-ts", "%s", res.Request.URL.String())
 		assert.Equal(t, identifier, gjson.GetBytes(body2, "identity.traits.subject").String(), "%s", body2)
-		assert.Equal(t, gjson.GetBytes(body1, "sid").String(), gjson.GetBytes(body2, "sid").String(), "%s\n\n%s\n", body1, body2)
+		assert.Equal(t, gjson.GetBytes(body1, "id").String(), gjson.GetBytes(body2, "id").String(), "%s\n\n%s\n", body1, body2)
 	})
 }

selfservice/strategy/password/registration_test.go

@@ -345,7 +345,7 @@ func TestRegistration(t *testing.T) {
 				assert.Contains(t, res.Request.URL.String(), publicTS.URL+password.RouteRegistration)
 				assert.Equal(t, `registration-identifier-8-api`, gjson.GetBytes(body, "identity.traits.username").String(), "%s", body)
 				assert.NotEmpty(t, gjson.GetBytes(body, "session_token").String(), "%s", body)
-				assert.NotEmpty(t, gjson.GetBytes(body, "session.sid").String(), "%s", body)
+				assert.NotEmpty(t, gjson.GetBytes(body, "session.id").String(), "%s", body)
 			})
 
 			t.Run("type=browser", func(t *testing.T) {

session/session.go

@@ -14,7 +14,7 @@ import (
 // swagger:model session
 type Session struct {
 	// required: true
-	ID uuid.UUID `json:"sid" faker:"-" db:"id"`
+	ID uuid.UUID `json:"id" faker:"-" db:"id"`
 
 	Active bool `json:"active" db:"active"`