OIDCClientConfiguration cannot be found in a subwiki

When the OIDC authenticator is called in the context of a subwiki, wiki configurations may not be correctly picked up, as https://github.com/xwiki-contrib/oidc/blob/0dbc59e8da63f7c50cc31a043564bd0ead93fa0b/oidc-authenticator-configuration/src/main/java/org/xwiki/contrib/oidc/auth/internal/store/DefaultOIDCClientConfigurationStore.java#L63 will not look into the main wiki configurations.