Improve the callback uri format and customization. (#4664)

* Remove unused SUPPORT_EMAIL_ADDRESS

* Improve the callback uri format and customization.

Use io.element.android for the scheme of Oidc redirection for Element X.
For nightly the scheme will be io.element.android.nightly
For debug the scheme will be  io.element.android.debug

Element Pro is using `io.element`

plugins/src/main/kotlin/config/BuildTimeConfig.kt

@@ -21,7 +21,6 @@ object BuildTimeConfig {
     val URL_ACCEPTABLE_USE: String? = null
     val URL_PRIVACY: String? = null
     val URL_POLICY: String? = null
-    val SUPPORT_EMAIL_ADDRESS: String? = null
     val SERVICES_MAPTILER_BASE_URL: String? = null
     val SERVICES_MAPTILER_APIKEY: String? = null
     val SERVICES_MAPTILER_LIGHT_MAPID: String? = null