set register_when_network_is_up to default value (1).

Add possibility to assiocate tags with tests and to run the only the tests corresponding with a specific tag with the --tag option.

make sure in case of SRTP DTLS enabled, ice reinvite is disabled & mandatory encryption is activated

remove linphone_core_create_default_call_parameters() because this function is dangerous and error prone.
Indeed, it cannot guarantee that the created call params are compatible with the call being accepted or updated.
For doing an outgoing call there is no problem in using it but linphone_core_create_call_params() is better and hard to mis-use.

tester: update bc_tester_utils and fix some tests - disable stderr for sipp because corrupting output is not great at all

chat: refactoring it to always invoke callbacks when changing state, reenable disabled tests and add two new file upload tests where liblinphone should not crash while it does currently

fix multiple memory leaks, mainly in gtk UI