[FEAT] Enable INVALIDATE_REFRESH_TOKENS

- It's possible to detect if refresh tokens are used more than once, if
it's used more than it's a indication of a replay attack and it should
invalidate the associated access token. This behavior is controlled by
the `INVALIDATE_REFRESH_TOKENS` setting.
- Altough in a normal scenario where TLS is being used, it should be
very hard to get to situation where replay attacks are being used, but
this is better safe than sorry.
- Enable `INVALIDATE_REFRESH_TOKENS` by default.

modules/setting/oauth2.go

@@ -104,7 +104,7 @@ var OAuth2 = struct {
 	Enabled:                    true,
 	AccessTokenExpirationTime:  3600,
 	RefreshTokenExpirationTime: 730,
-	InvalidateRefreshTokens:    false,
+	InvalidateRefreshTokens:    true,
 	JWTSigningAlgorithm:        "RS256",
 	JWTSigningPrivateKeyFile:   "jwt/private.pem",
 	MaxTokenLength:             math.MaxInt16,