tsearle created an issue (kamailio/kamailio#4273)

### Description

For forking media and sip rec flows the following rtpengine commands need to be exposed * subscribe reqeust * subscribe answer * unsubscribe

currently these commands are only exposed for internal api use.

This patch exposes these commands in both kemi and the kamailio scripting language ### Possible Solutions

merge the corresponding pr

### Additional Information

* **Kamailio Version** - output of `kamailio -v`

``` version: kamailio 6.0.1 (aarch64/linux) flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, MEM_JOIN_FREE, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT-NOSMP, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLOCKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_SEND_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: unknown compiled with gcc 12.2.0```

* **Operating System**:

``` Linux dev-ew1-blue-app-208 6.1.0-37-cloud-arm64 #1 SMP Debian 6.1.140-1 (2025-05-22) aarch64 GNU/Linux ```