Improve startup error message when bind on http port fails

[psteniusubi]

Fixing issue WebOfTrust/keripy#455 for keria

New startup error messages

$ keria start
Traceback (most recent call last):
  File "/home/uroot/.local/bin/keria", line 33, in <module>
    sys.exit(load_entry_point('keria', 'console_scripts', 'keria')())
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 31, in main
    raise ex
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 25, in main
    doers = args.handler(args)
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 20, in <lambda>
    parser.set_defaults(handler=lambda args: launch(args))
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 74, in launch
    runAgent(name=args.name,
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 97, in runAgent
    doers.extend(agenting.setup(name=name, base=base, bran=bran,
  File "/home/uroot/keria/src/keria/app/agenting.py", line 63, in setup
    raise RuntimeError(f"cannot create boot http server on port {bootPort}")
RuntimeError: cannot create boot http server on port 3903

$ keria start -B 33903
Traceback (most recent call last):
  File "/home/uroot/.local/bin/keria", line 33, in <module>
    sys.exit(load_entry_point('keria', 'console_scripts', 'keria')())
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 31, in main
    raise ex
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 25, in main
    doers = args.handler(args)
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 20, in <lambda>
    parser.set_defaults(handler=lambda args: launch(args))
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 74, in launch
    runAgent(name=args.name,
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 97, in runAgent
    doers.extend(agenting.setup(name=name, base=base, bran=bran,
  File "/home/uroot/keria/src/keria/app/agenting.py", line 83, in setup
    raise RuntimeError(f"cannot create admin http server on port {adminPort}")
RuntimeError: cannot create admin http server on port 3901

$ keria start -B 33903 -a 33901
Traceback (most recent call last):
  File "/home/uroot/.local/bin/keria", line 33, in <module>
    sys.exit(load_entry_point('keria', 'console_scripts', 'keria')())
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 31, in main
    raise ex
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 25, in main
    doers = args.handler(args)
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 20, in <lambda>
    parser.set_defaults(handler=lambda args: launch(args))
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 74, in launch
    runAgent(name=args.name,
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 97, in runAgent
    doers.extend(agenting.setup(name=name, base=base, bran=bran,
  File "/home/uroot/keria/src/keria/app/agenting.py", line 108, in setup
    raise RuntimeError(f"cannot create local http server on port {httpPort}")
RuntimeError: cannot create local http server on port 3902

Error message before the fix

$ keria start
The Agency is loaded and waiting for requests...
Traceback (most recent call last):
  File "/home/uroot/.local/bin/keria", line 33, in <module>
    sys.exit(load_entry_point('keria', 'console_scripts', 'keria')())
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 31, in main
    raise ex
  File "/home/uroot/keria/src/keria/app/cli/keria.py", line 25, in main
    doers = args.handler(args)
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 20, in <lambda>
    parser.set_defaults(handler=lambda args: launch(args))
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 74, in launch
    runAgent(name=args.name,
  File "/home/uroot/keria/src/keria/app/cli/commands/start.py", line 107, in runAgent
    directing.runController(doers=doers, expire=expire)
  File "/home/uroot/keripy/src/keri/app/directing.py", line 665, in runController
    doist.do(doers=doers)
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/base/doing.py", line 156, in do
    self.recur()  # increments .tyme runs recur context
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/base/doing.py", line 275, in recur
    tock = dog.send(self.tyme)  # yielded tock == 0.0 means re-run asap
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/base/doing.py", line 568, in do
    self.done = self.recur(tyme=tyme)
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/core/http/serving.py", line 1359, in recur
    self.server.service()
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/core/http/serving.py", line 846, in service
    self.serviceConnects()
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/core/http/serving.py", line 765, in serviceConnects
    self.servant.serviceConnects()
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/core/tcp/serving.py", line 292, in serviceConnects
    self.serviceAxes()
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/core/tcp/serving.py", line 269, in serviceAxes
    self.serviceAccepts()  # populate .axes
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/core/tcp/serving.py", line 196, in serviceAccepts
    cs, ca = self.accept()
  File "/home/uroot/.local/lib/python3.10/site-packages/hio/core/tcp/serving.py", line 182, in accept
    cs, ca = self.ss.accept()  # virtual connection (socket, host address)
AttributeError: 'NoneType' object has no attribute 'accept'

[pfeairheller]

Can you please fix the failing tests in the PR so we can get it merged?

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (843759f) 91.38% compared to head (d757f40) 91.34%.

Files	Patch %	Lines
src/keria/app/agenting.py	50.00%	3 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           development     #134      +/-   ##
===============================================
- Coverage        91.38%   91.34%   -0.05%     
===============================================
  Files               35       35              
  Lines             5818     5825       +7     
===============================================
+ Hits              5317     5321       +4     
- Misses             501      504       +3     

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[psteniusubi]

@pfeairheller - Tests are passing now