Merge branch 'bugfix/mdns_security_issues' into 'master'

Merge branch 'bugfix/mdns_security_issues' into 'master'

Bugfix/mdns security issues

Fixes a series of security issues with MDNS.

STACK-SMASH: https://github.com/espressif/esp-idf/blob/dd3f18d2d88ee78909d4af2840dfdf0b9f715f28/components/mdns/mdns.c#L494:
The sprintf is not limited. We can execute the sprintf codeflow as
many times as we want, allowing arbitrary long data being written
into stack.

PACKET-OF-DEATH:
https://github.com/espressif/esp-idf/blob/dd3f18d2d88ee78909d4af2840dfdf0b9f715f28/components/mdns/mdns.c#L502.
The compare allows equal, and thus jumping back to it self infinite
recursion -> guaranteed crash

TXT-SMASH: https://github.com/espressif/esp-idf/blob/dd3f18d2d88ee78909d4af2840dfdf0b9f715f28/components/mdns/mdns.c#L1381
The loop does not check on reaching a->txt maximum size (1024),
resulting in stack overflow.

See merge request !576