Add home pages for all languages

[jmformenti]

Currently, there is only a home page for the English language. We need to create equivalent pages for the other languages: Català, Español, Galego, Português.

Implementation Hints

• For each language, add an entry here: https://philobiblon.cog.berkeley.edu/wiki/En_PhiloBiblonViewer_Index, like _enWelcome for English.
• Translate the welcome page from https://bancroft.berkeley.edu/philobiblon/ to wiki page format, similar to the English page: https://philobiblon.cog.berkeley.edu/wiki/En_Welcome

Definition of Done

1. Check if the English welcome page is updated and update it if necessary.
2. Create a new welcome page for each language and verify its visualization in PBUI.

[faulhaber]

Finish the English Welcome page, but adding the Welcome pages in the other languages is less important than building out the subsidiary web pages, as seen in Issue # and adding the search filters for the various tables. Delete the BETA / BIPA / BITECA / BITAGAP links at the bottom of the page since they are now redundant.

[faulhaber]

Josep noted that in fact all of the Welcome pages for the other languages have also been finished.