Upgrade to Angular 19 or 20

[tdonohue]

Description

Angular 19 is available as is Angular 20, so we should upgrade our User Interface to support that version.

Resources:

• https://blog.angular.dev/announcing-angular-v20-b5c9c06cf301
• https://blog.angular.dev/meet-angular-v19-7b29dfd05b84
• https://angular.dev/update-guide?v=18.0-19.0
• Our prior upgrade to 18.0: Upgrade to angular v18 #3717

Tentatively scheduling for 10.0, but this needs a volunteer to investigate the complexity of this upgrade.

[max-nuding]

Active support for angular 19 has already ended, LTS support for v19 ends in May 2026, shortly after the planned DSpace 10 release. I think we should upgrade to angular 20 and skip 19.

I also took a look at their upgrade guide from v19 to v20. It looks like a manageable amount of work and not a huge complexity. Will need lots of testing of course