refactor: Improve self group announcement mechanism

[JFreegman]

Self announcements are now refreshed when either our TCP or UDP connection changes
as long as one or the other is connected. We no longer spam the DHT needlessly
when our TCP status updates. In addition, we always attempt to refresh
our announcements every 10 minutes if possible.

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This change is 

[codecov]

Codecov Report

Merging #1581 into ngc will decrease coverage by 0.13%.
The diff coverage is 58.33%.

@@            Coverage Diff             @@
##              ngc    #1581      +/-   ##
==========================================
- Coverage   81.35%   81.21%   -0.14%     
==========================================
  Files          95       95              
  Lines       20507    20528      +21     
==========================================
- Hits        16683    16672      -11     
- Misses       3824     3856      +32     

Impacted Files	Coverage Δ
toxcore/group_chats.c	67.95% <53.33%> (-1.54%)	⬇️
toxcore/Messenger.c	86.21% <83.33%> (+0.15%)	⬆️
toxcore/crypto_core_test.cc	89.28% <0.00%> (-10.72%)	⬇️
toxav/groupav.c	81.78% <0.00%> (-1.22%)	⬇️
toxcore/LAN_discovery.c	83.65% <0.00%> (-0.97%)	⬇️
auto_tests/group_state_test.c	98.26% <0.00%> (-0.87%)	⬇️
toxcore/onion_client.c	96.42% <0.00%> (+0.57%)	⬆️
toxcore/net_crypto.c	94.50% <0.00%> (+0.73%)	⬆️
... and 1 more

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