Fixes #26390: API Accounts model needs to be consistent accross backend and frontend

[clarktsiory]

https://issues.rudder.io/issues/26390

• Make expiration policy be a specific ADT instead of two Option with logic on both. Refactoring the logic leads us to change the default expiration date to 30 days instead of 1 month.
• Same for the token, which is either a system one, or an account token (the mandatory expiration date was kept as is to prevent changing the schema)
• Add typing for AuthorizationType in Elm to avoid manipulations on strings

TODO :

• [ ] retarget to 9.1
• [ ] remove pom.xml change
• [ ] make clearer public API account vs system API account separation with a dedicated subtype

[clarktsiory]

PR updated with a new commit

[clarktsiory]

PR updated with a new commit

[clarktsiory]

PR updated with a new commit

[clarktsiory]

PR updated with a new commit