[test] Test apps improvements + build break fixes with logging off

[ethouris]

Changes summary:

1. Fixes for compiling with ENABLE_LOGGING=OFF that got a build break (some may additionally follow in the application files):

• srtcore/common.cpp
• srtcore/crypto.cpp
• srtcore/crypto.h

2. Small bugfixes and improvements in the test application, mainly connected with ability to test with unusual scenarios:

• apps/apputil.cpp -- Bugfix for correct handling -1 numbers in option arguments
• testing/srt-test-live.cpp -- Added retry option
• testing/srt-test-mpbond.cpp -- Fixed build break when logging is on
• testing/testmedia.cpp -- Fix for proper handling async group connection; handler for retry

[ethouris]

Bugfix for handling numeric negative arguments in option parser.

[ethouris]

Added a -retry option that stubbornly tries to reconnect when the connection was broken. The argument is a number of times to retry, -1 is unlimited, when a is added to the number, it means it should retry no matter what the reason was (otherwise it only retries if it was timeout).

[maxsharabayko]

Approved.
The question is how to qualify this PR.

• It touches the core, but only around exposing some logging staff to apps if built with logging disabled.
• It fixes building of testing apps.
• It fixes a bug in Options Parser
• It adds the new command-line option -retry to srt-test-live.

[tests] is for unit tests. Testing apps are [apps].
So either [core] or [apps] 🤔

[maxsharabayko]

Touching [core] should be of higher importance, but those changes are pretty minor, and changes to [apps] are more notable. Therefore let it be [apps].