* Adding a help button on top of the chat, that links to the online documentation on frama.io.
* Replaced github.io documentation links by frama.io documentation.
* Adding links to the documentation in the diagnostic tool.
* the front-end now use global constants, based on the translation key
* build-client.js use the ESBuild "define" directive to replace these
globals at compile time, by the english value
* build:client must now be called after build:languages
* moving the loadLoc and loc backend functions in a separate lib
