BBOT Server Improvements

[TheTechromancer]

Makes several improvements for BBOT server; mainly around scan statuses, to ensure the dispatcher correctly reports on the status of the scan even when it's cancelled.

[codecov]

Codecov Report

Attention: Patch coverage is 86.82635% with 22 lines in your changes missing coverage. Please review.

Project coverage is 93%. Comparing base (d490146) to head (01767e4).
Report is 499 commits behind head on 3.0.

Files with missing lines	Patch %	Lines
bbot/modules/base.py	37%	14 Missing ⚠️
bbot/scanner/scanner.py	86%	5 Missing ⚠️
bbot/modules/internal/excavate.py	40%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             3.0   #2411     +/-   ##
=======================================
+ Coverage     93%     93%     +1%     
=======================================
  Files        396     412     +16     
  Lines      30535   33367   +2832     
=======================================
+ Hits       28223   30859   +2636     
- Misses      2312    2508    +196     

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