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

package.json

@@ -264,6 +264,7 @@
         "file-loader": "^6.0.0",
         "html-webpack-plugin": "^5.5.3",
         "husky": "^9.0.0",
+        "identity-obj-proxy": "^3.0.0",
         "jest": "^29.6.2",
         "jest-canvas-mock": "^2.5.2",
         "jest-environment-jsdom": "^29.7.0",