Use empty senders list

[roxblnfk]

What was changed

Trap server can be started without senders or with Frontend server only.

# Run with default ports and console sender
trap run

# Run with UI on port 8080, listen default ports, and use console sender
trap run --ui=8080

# Run with UI, disable console sender
trap run --ui=8080 -s
# Equals to
trap run --ui=8080 --sender=""

Checklist

• Closes Sender config #199
• Tested
  • Tested manually
  • Unit tests added
• Documentation

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 25.14%. Comparing base (1560e7d) to head (bb65e37).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/Command/Run.php	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #200      +/-   ##
============================================
+ Coverage     24.89%   25.14%   +0.25%     
  Complexity     1359     1359              
============================================
  Files           158      158              
  Lines          4327     4215     -112     
============================================
- Hits           1077     1060      -17     
+ Misses         3250     3155      -95     

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