feat(server)!: oauth encryption algorithm setting (#6818)

* feat: add oauth signing algorithm setting

* chore: open api

* chore: change default to RS256

* feat: test and clean up

---------

Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>

open-api/immich-openapi-specs.json

@@ -9679,6 +9679,9 @@
           "scope": {
             "type": "string"
           },
+          "signingAlgorithm": {
+            "type": "string"
+          },
           "storageLabelClaim": {
             "type": "string"
           }
@@ -9694,6 +9697,7 @@
           "mobileOverrideEnabled",
           "mobileRedirectUri",
           "scope",
+          "signingAlgorithm",
           "storageLabelClaim"
         ],
         "type": "object"