Portscanner Rework

[TheTechromancer]

This PR simplifies the port scanner situation in BBOT by deleting nmap and replacing it with a brand-new masscan implementation, augmented to handle hostnames.

This accomplishes a few things:

• helps relieve some of the confusion around there being two port scanners
• better performance (masscan is much faster than nmap)

TODO:

• [x] Does masscan work with IPv6? (answer: YES)
  • [x] localhost? Multiple interfaces? (answer: NO, but meh)
• [x] Handle IPv6 abort

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 81.18280% with 35 lines in your changes are missing coverage. Please review.

Project coverage is 92%. Comparing base (a22cb9b) to head (b9c2e23).

Files	Patch %	Lines
bbot/modules/portscan.py	80%	32 Missing :warning:
...step_2/module_tests/test_module_asset_inventory.py	86%	2 Missing :warning:
bbot/modules/internal/speculate.py	0%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## bbot-2.0 #1375 +/- ## ========================================= + Coverage 92% 92% +1% ========================================= Files 343 340 -3 Lines 23236 23048 -188 ========================================= - Hits 21316 21156 -160 + Misses 1920 1892 -28 ```

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