Backport iOS fixes : Fix crash when setting default account to nil; check if the core is Shutdown or Off before updating push informations

liblinphone!2022

Fix sip address table creation when database connection string containts utf8mb4 as charset, on mariadb 5.5 (mitigates Exception while creating or updating the database's schema : Specified key was too long; max key length is 767 bytes while executing)
Added warning comments in case utf8mb4 varchar columns > 255 were to be indexed [skip ci]

Make DTLS-SRTP to start immediately after the default candidate pair is verified by ICE. This saves time to establish the audio stream.

Look if me is focus to kow whether conference is local or remote

Revert "Add an insenstive case search function to replace std::find without having to deal with locale."
Revert "Magic Search : Insensitive case for special character set by using wstring."
Revert "MagicSearch for case insensitive : replace tolower by regex in order to work without locale."

Add an alternative to std::find for insensitive case searches in bctoolbox.

Restore previous behaviour. Do not return belle_sip_source_t when scheduling task on the main loop. Create timer instead to queue a task on the main loop in order to be able to cancel it should the call end before its execution

Fix an issue where audio stops when trying to send a DTMF while no telephone-event payload types are configured in the session.

IOS Audio route - Fix incorrect event change, do not add UNKNOWN type audio devices to the device list