Add background task to protect Core startup on Android, and fix a potential bad call state transition in case of duplicated calls.

vector

Fix an issue where SDP has wrong connectivity type (ipv6, ipv4) when restarting an INVITE after a network disconnection in early stage of a call.
Fix iOS SDK with tunnel.

    transfer_message_upload_cancelled to avoid it to be dealt with in the
    following test

Detect video codecs hardware-accelerated only on Mac OS. Software ones are not usable for real-time encoding. As a side effect, HEVC is no longer available for M1/M2 processors in x86_64 emulation.

Fix resending file transfer with 'null' file. On cancellation, the filetransfer is not reset that lead the message to have its Content as not isFile().
Then, next call to send() was done with no isFile() in its contents.
- Restore the content.

- Use pt->normal_bitrate only if stream->ms.max_target_bitrate is not set.

Default layout to ActiveSpeaker to ensure backward compatibility as the the server may receive SDP streams with an unknwon content.

Update README.md for iOS compilation, and change the use of INVITE with replaces header, so that we use it only when we are sure that the callee got the first INVITE.
Fix build with tunnel for iOS and MacOS.

Update MainDb version to 1.0.30 to handle compatibility issues when upgrading from release/5.2 to release/5.3

Add setting to disable RTP volumes, because implementaitons that do not ignore RTP extension headers they do not support.