[MM-55140] Spacing between buttons is incorrect in channel dropdown > convert to private channel in mobile web view (#25491)

* button gap fixed for mobile modal

* modal footer button gap fixed for mobile (Web App)

* modal footer button gap fixed for mobile (Web App).

* changes to fix ci/lint

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Co-authored-by: Mattermost Build <build@mattermost.com>

webapp/channels/src/sass/components/_modal.scss

@@ -137,7 +137,11 @@
     }
 
     .modal-footer {
+        display: flex;
+        flex-wrap: wrap;
+        justify-content: end;
         background: var(--center-channel-bg);
+        grid-row-gap: 8px;
 
         &.modal-footer--invisible {
             overflow: hidden;