Move Flex & Box component into shared component folder (#30357)

* refactor: move Flex component in shared components

* refactor: update imports

* refactor: remove Flex pcss file

* fix: Flex component css override

* test: update snapshots

* fix: html export

* chore: add css module support to jest

* chore: keep old copyright

* refactor: change `mx_Flex` in `ErrorView` to `mx_ErrorView_flexContainer`

* test: update snapshots

* refactor: move Box component in shared components

* refactor: update import and css override

* test: update snapshots

res/css/views/right_panel/_RoomSummaryCard.pcss

@@ -32,7 +32,7 @@ Please see LICENSE files in the repository root for full details.
         padding: 0 12px;
         color: var(--cpd-color-text-secondary);
 
-        .mx_Box {
+        .mx_RoomSummaryCard_topic_box {
             width: 100%;
         }
 

res/css/views/right_panel/_UserInfo.pcss

@@ -108,11 +108,6 @@ Please see LICENSE files in the repository root for full details.
             margin: 0;
             font-size: $font-20px;
             line-height: $font-25px;
-
-            /* E2E icon wrapper */
-            .mx_Flex > span {
-                display: inline-block;
-            }
         }
 
         .mx_UserInfo_profile_name {