chore(example): add supported signing algorithms to RP

[muhlemmer]

This change adds supported signing algorithms the the app example's RP.

This algorithms will be added to zitadel in zitadel/zitadel#8449. This change makes the example work with any of the key types that can be configured in zitadel.

Related to zitadel/zitadel#8031

Definition of Ready

• I am happy with the code
• Short description of the feature/issue is added in the pr description
• PR is linked to the corresponding user story
• Acceptance criteria are met
• All open todos and follow ups are defined in a new ticket and justified
• Deviations from the acceptance criteria and design are agreed with the PO and documented.
• No debug or dead code
• My code has no repetitions
• Critical parts are tested automatically
• Where possible E2E tests are implemented
• Documentation/examples are up-to-date
• All non-functional requirements are met
• Functionality of the acceptance criteria is checked manually on the dev system.