[FIX] portal: change width of portal modal to match backend

Some features are common to portal and backend, such as the sign modal in
enterprise.

This commit uniformize the width of the modal to make it more consistent between
the two by default. Of course themes can still customize this behavior.

closes odoo/odoo#29521

addons/portal/static/src/scss/bootstrap_overridden.scss

@@ -15,3 +15,8 @@ $font-size-sm: (12 / 16) * 1rem;
 
 $btn-padding-y-sm: (1 / 16) * 1rem;
 $btn-padding-x-sm: (5 / 16) * 1rem;
+
+// Modals
+
+$modal-lg: $o-modal-lg;
+$modal-md: $o-modal-md;

addons/web/static/src/scss/bootstrap_overridden.scss

@@ -133,8 +133,8 @@ $modal-inner-padding: $o-horizontal-padding;
 
 // FIXME $modal-title-padding ?
 
-$modal-lg: 980px;
-$modal-md: 650px;
+$modal-lg: $o-modal-lg;
+$modal-md: $o-modal-md;
 
 // Breadcrumbs
 

addons/web/static/src/scss/primary_variables.scss

@@ -65,6 +65,9 @@ $o-sheet-vpadding: 24px;
 $o-notification-error-bg-color: #F16567;
 $o-notification-info-bg-color: #FCFBEA;
 
+$o-modal-lg: 980px;
+$o-modal-md: 650px;
+
 // Needed for having no spacing between sheet and mail body in mass_mailing:
 // Different required cancel paddings between web and web_enterprise
 $o-sheet-cancel-tpadding: 0px;