React 18 introduced automatic batching which tries to avoid unnecessary
re-rendering (https://react.dev/blog/2022/03/08/react-18-upgrade-guide#automatic-batching).
In some components based on react-virtualized (e.g. tag selector),
it leads to visible lagginess on scroll via keypress or
mouse wheel (not trackpad). This patch wraps setState of the scroll handler
of react-virtualized with ReactDOM.flushSync, which opts out
of automatic batching.
Fixes: #4368
* Omit msg-ref-only strings from Transifex JSON
* Fix msg-ref-only strings not included in translated .ftl files
* Update ftl-tx. Simplify localize-ftl script.
* Tweak FTL -> JSON conversion to produce a single file
- Remove directories that should no longer be present in the build.
- Add watching for new files.
- Add debounce and batching to reduce verbosity and avoid needless cleanup and "add to omni" steps
when entire directories are affected.
- Use locale directories for JSON files, since that's where the
Transifex client will interact with them
- Skip non-locale directories (e.g., don't create an .ftl file for
.DS_Store)
- Other minor simplification
