Core CAPI is missing the realm_app_config_get_sync_client_config() implementation

[sync-by-unito]

In the realm.h file, there is a definition for realm_app_config_get_sync_client_config() to retrieve the realm_sync_client_config_t reference from the realm_app_config_t structure, since it is a member of this struct. Unfortunately, only the function header is provided and there is no implementation for it.
Add the implementation and add or update at least one test that verifies this functionality.

[sync-by-unito]

➤ PM Bot commented:

Jira ticket: RCORE-2201

[sync-by-unito]

➤ michael-wb commented:

It seems to be better to restore the original realm_app_config_set_sync_client_config() function, since there are two different types of references to the SyncClientConfig in the C_API:

• a pointer to the struct stored in the AppConfig
• a WrapC object when using a SyncClientConfig structure separate from the AppConfig

Only the second one is is compatible with the realm_sync_client_config_t structure used to wrap the SyncClientConfig structure in the C_API.