feat(gui): add option to limit bandwidth in LAN to Settings (ref #10046) (#10182)

gui: Add option to limit bandwidth in LAN to Settings (ref #10046)

Currently, the option to limit bandwidth in LAN is available only via
the Advanced Configuration, which makes it difficult to discover by new
users, who are confused why their bandwidth limits are not working.

For this reason, make the option easily discoverable by adding it
directly to Connections in the normal Settings in the Web GUI.

Ref:
https://github.com/syncthing/syncthing/issues/10046
https://github.com/syncthing/syncthing/issues/2046
https://github.com/syncthing/syncthing/issues/2569
https://forum.syncthing.net/t/upload-rate-not-work/19025

https://forum.syncthing.net/t/rate-limits-dont-work-over-lan-in-v1-20-1/18521

Signed-off-by: Tomasz Wilczyński <twilczynski@naver.com>

### Screenshots


![image](https://github.com/user-attachments/assets/bd38b3ab-a053-4992-ba86-7fb8b3ba09d9)

Signed-off-by: Tomasz Wilczyński <twilczynski@naver.com>

gui/default/assets/lang/lang-en.json

@@ -227,6 +227,7 @@
     "Learn more": "Learn more",
     "Learn more at {%url%}": "Learn more at {{url}}",
     "Limit": "Limit",
+    "Limit Bandwidth in LAN": "Limit Bandwidth in LAN",
     "Listener Failures": "Listener Failures",
     "Listener Status": "Listener Status",
     "Listeners": "Listeners",

gui/default/syncthing/settings/settingsModalView.html

@@ -210,6 +210,17 @@
               </div>
             </div>
           </div>
+          <div class="row">
+            <div class="col-md-6">
+              <div class="form-group">
+                <div class="checkbox">
+                  <label>
+                    <input id="LimitBandwidthInLan" type="checkbox" ng-model="tmpOptions.limitBandwidthInLan" /> <span translate>Limit Bandwidth in LAN</span>
+                  </label>
+                </div>
+              </div>
+            </div>
+          </div>
           <div class="row">
             <div class="col-md-6">
               <div class="form-group">