Add dropdown for boost privacy in boost confirmation modal (#15704)

* Various dropdown code quality fixes

* Prepare support for privacy selection in boost modal

* Add dropdown for boost privacy in boost confirmation modal

app/javascript/mastodon/actions/boosts.js

@@ -0,0 +1,29 @@
+import { openModal } from './modal';
+
+export const BOOSTS_INIT_MODAL = 'BOOSTS_INIT_MODAL';
+export const BOOSTS_CHANGE_PRIVACY = 'BOOSTS_CHANGE_PRIVACY';
+
+export function initBoostModal(props) {
+  return (dispatch, getState) => {
+    const default_privacy = getState().getIn(['compose', 'default_privacy']);
+
+    const privacy = props.status.get('visibility') === 'private' ? 'private' : default_privacy;
+
+    dispatch({
+      type: BOOSTS_INIT_MODAL,
+      privacy
+    });
+
+    dispatch(openModal('BOOST', props));
+  };
+}
+
+
+export function changeBoostPrivacy(privacy) {
+  return dispatch => {
+    dispatch({
+      type: BOOSTS_CHANGE_PRIVACY,
+      privacy,
+    });
+  };
+}

app/javascript/mastodon/actions/interactions.js

@@ -41,11 +41,11 @@ export const UNBOOKMARK_REQUEST = 'UNBOOKMARKED_REQUEST';
 export const UNBOOKMARK_SUCCESS = 'UNBOOKMARKED_SUCCESS';
 export const UNBOOKMARK_FAIL    = 'UNBOOKMARKED_FAIL';
 
-export function reblog(status) {
+export function reblog(status, visibility) {
   return function (dispatch, getState) {
     dispatch(reblogRequest(status));
 
-    api(getState).post(`/api/v1/statuses/${status.get('id')}/reblog`).then(function (response) {
+    api(getState).post(`/api/v1/statuses/${status.get('id')}/reblog`, { visibility }).then(function (response) {
       // The reblog API method returns a new status wrapped around the original. In this case we are only
       // interested in how the original is modified, hence passing it skipping the wrapper
       dispatch(importFetchedStatus(response.data.reblog));