feat: display all accessible oidc clients in the dashboard (#832)

Co-authored-by: Kyle Mendell <ksm@ofkm.us>

backend/internal/dto/oidc_dto.go

@@ -159,3 +159,8 @@ type OidcClientPreviewDto struct {
 	AccessToken map[string]any `json:"accessToken"`
 	UserInfo    map[string]any `json:"userInfo"`
 }
+
+type AccessibleOidcClientDto struct {
+	OidcClientMetaDataDto
+	LastUsedAt *datatype.DateTime `json:"lastUsedAt"`
+}