2216 add tcprelay

[cakekoa]

What does this PR do?

Addresses part of #2216.

Created the TCPRelay class. It is currently implemented as described in the issue, except that it doesn't have

PR Checklist

• Have you added an explanation of what your changes do and why you'd like to include them?
• Is the TravisCI build passing?
• Was the CHANGELOG.md updated to reflect the changes?
• Was the documentation framework updated to reflect the changes?
• Have you checked that you haven't introduced any duplicate code?

Testing Checklist

• Added relevant unit tests?
• Have you successfully tested your changes locally? Elaborate:

  I have only run the unit tests

• If applicable, add screenshots or log transcripts of the feature working

[codecov]

Codecov Report

Merging #2231 (b179f60) into tcp-relay (4cbefed) will decrease coverage by 0.10%.
The diff coverage is 53.55%.

❗ Current head b179f60 differs from pull request most recent head 1e0b26a. Consider uploading reports for the commit 1e0b26a to get more accurate results

@@              Coverage Diff              @@
##           tcp-relay    #2231      +/-   ##
=============================================
- Coverage      58.02%   57.92%   -0.11%     
=============================================
  Files            514      520       +6     
  Lines          13657    13810     +153     
=============================================
+ Hits            7925     7999      +74     
- Misses          5732     5811      +79     

Impacted Files	Coverage Δ
monkey/infection_monkey/network/relay/tcp.py	26.66% <26.66%> (ø)
...ion_monkey/network/relay/tcp_connection_handler.py	34.48% <34.48%> (ø)
...infection_monkey/network/relay/tcp_pipe_spawner.py	42.10% <42.10%> (ø)
monkey/infection_monkey/tcp_relay.py	66.66% <66.66%> (ø)
...fection_monkey/network/relay/relay_user_handler.py	79.41% <79.41%> (ø)
monkey/infection_monkey/network/relay/__init__.py	100.00% <100.00%> (ø)
...engers/exploit_intercepting_telemetry_messenger.py	100.00% <100.00%> (ø)
monkey/common/utils/code_utils.py	89.28% <0.00%> (-1.90%)	⬇️
...nkey/monkey_island/cc/resources/pba_file_upload.py	90.62% <0.00%> (-0.42%)	⬇️
monkey/infection_monkey/master/propagator.py	98.98% <0.00%> (-0.02%)	⬇️
... and 25 more

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