locale aliases in i18n routing strategy

[samuelstroschein]

Context

https://github.com/orgs/opral/discussions/3368#discussioncomment-11920702

A user needs to alias locales to turn paths like /en/page into /english/page for backwards compatibility.

Proposal

Offer a strategy option to alias locales.

strategy: {
  // ...
+  localeAlias = {
+    en: "english",
+    de: "deutsch",
+ }
}

[samuelstroschein]

@d1d4r can you clarify if you want both locale and the alias to work, or just the alias?

both working

/en/page ✅ 
/english/page ✅ 

only alias working

/en/page 🔴  
/english/page ✅ 

[d1d4r]

i just need alias, but if possible it's great work with both

[samuelstroschein]

I'll go for both working because then you can incrementally migrate to one or the other

[samuelstroschein]

@d1d4r please give feedback on #359 (comment)