bootstrap: fix minor issues with profile picture cropping

* Add required [1] "display: block;" style property to img element
* Fix image overflow in modal. As cropper size inherits from img's parent element [2] (including padding according to my research), we need to wrap modal body into another div that has the padding we want.
* Remove ability [3] to click away to dismiss the modal as it often interfered with user interaction when cropping.

[1] https://github.com/fengyuanchen/cropperjs/tree/v1?tab=readme-ov-file#example
[2] https://github.com/fengyuanchen/cropperjs/tree/v1?tab=readme-ov-file#notes
[3] https://getbootstrap.com/docs/4.0/components/modal/#options

See merge request bde/nk20!301

apps/member/templates/member/picture_update.html

@@ -20,12 +20,14 @@ SPDX-License-Identifier: GPL-3.0-or-later
       </form>
     </div>
     <!-- MODAL TO CROP THE IMAGE -->
-    <div class="modal fade" id="modalCrop">
+    <div class="modal fade" id="modalCrop" data-backdrop="static">
       <div class="modal-dialog">
         <div class="modal-content">
-          <div class="modal-body">
-            <img src="" id="modal-image" style="max-width: 100%;">
-          </div>
+            <div class="modal-body-wrapper" style="width: 500px; height: 500px; padding: 16px;">
+              <div class="modal-body" style="width: 100%; height: 100%; padding: 0">
+                <img src="" id="modal-image" style="display: block; max-width: 100%;">
+              </div>
+            </div>
           <div class="modal-footer">
             <div class="btn-group pull-left" role="group">
               <button type="button" class="btn btn-default" id="js-zoom-in">