vty: Introduce API vty_read_config_filep

This new API doesn't use host_config_set(), and allows passing a FILE*
from any source, not only a filesystem path.

Related: SYS#5369
Change-Id: I720ac04386261628c0798a1bfcaa91e2490a86c3
diff --git a/TODO-RELEASE b/TODO-RELEASE
index c5d4ee8..e57ffab 100644
--- a/TODO-RELEASE
+++ b/TODO-RELEASE
@@ -11,3 +11,4 @@
 libosmogsm      gsm0808_old_bss_to_new_bss_info ABI break (struct changes size), gsm0808_old_bss_to_new_bss_info_att_tlvdef symbol added
 libosmosim	osim_card_hdl		ABI + API breakage due to new struct members
 libosmocore	osmo_tdef_fsm_inst_state_chg	change default_timeout arg from unsigned long to long type (API breakage, not ABI)
+libosmovty      vty_read_config_filep   New API