L10n: messages-compiled.json are not compiled automatically by vite

[benbucksch]

Reproduction:

• Check out source code. Source tree should be clean, without additional files.
• cd app; yarn; yarn dev run
• cd e2; yarn; yarn dev run

Actual result:

• App fails to run
• Error: File l10n/locales/en/messages-compiled.json (imported by app/l10n/l10n.ts) is missing.
• Same for "de" etc. (not just "en")

Expected result:

• The vite plugin lingui(), added in vite.config.js and configured by lingui.config.ts, automatically compiles the l10n/locales/*/messages.json files to l10n/locales/*/messages-compiled.json files.
• The messages-compiled.json files are created in the temporary build directory, not in the source tree.

Implementation:

• In git commit 9d9ad62 (on branch jeremy/ui-localize), we imported the .po files directly, and vite lingui plugin was automatically compiling them to the JSON files that the app UI uses.
• Could we please do the same with the messages.json -> messages-compiled.json file compilation?

Impact:

• Build broken
• This is a regression by Localize UI #111 / UI: Localize #67

Workaround (until fixed):

• cd app; yarn run l10n:compile before yarn run dev - UPDATE: Workaround implemented in 256fd29. Please revert this commit, once this bug has been fixed properly.