Add server-wide and user-only federation controls (#133)

### Description

Completes #122

### Please confirm

- [x] I am the legal owner or represent the legal owner of all work submitted (including LLM-generated code, if any)
- [x] I consent to my changes being added to this FOSS project
- [x] I have confirmed that this does not add new errors or warnings with `utils/clippy.sh`
- [ ] This PR used LLMs to generate some or all of the code changes

Reviewed-on: https://git.ngram.ca/OpenJam/rc-servers/pulls/133

assets/templates/rc_society/garage_import.html.hbs

@@ -50,7 +50,7 @@
         {{else}}
           <input type="hidden" id="garage_id" name="garage_id" value="-1"/>
         {{/if}}
-        <div class="access-row-box">
+        <div class="access-row-box access-row-box-input">
           <label>Import with</label>
           <select id="plugin" name="plugin" required>
             {{#each form.importers}}
@@ -58,11 +58,11 @@
             {{/each}}
           </select>
         </div>
-        <div class="access-row-box">
-          <input type="file" id="files" name="files" required {{#if form.garage}} {{else}}multiple{{/if}} />
+        <div class="access-row-box access-row-box-input">
+          <input class="form-input-box" type="file" id="files" name="files" required {{#if form.garage}} {{else}}multiple{{/if}} />
         </div>
-        <div class="access-row-box">
-          <input type="submit" value="{{#if form.garage}}Override garage slot {{form.garage.slot}}{{else}}Import{{/if}}" />
+        <div class="access-row-box form-submit access-row-box-input">
+          <input class="form-submit-button" style="width:50%;" type="submit" value="{{#if form.garage}}Override garage slot {{form.garage.slot}}{{else}}Import{{/if}}" />
         </div>
       </div>
     </form>