318 implement pivotssh copy

[hulto]

What type of PR is this?

/kind feature
/kind eldritch-function

What this PR does / why we need it:

This PR adds the pivot.ssh_copy function to eldritch. This function is helpful for us so we can move files from one host to another allowing for initial deployment during Red v Blue training events.

Which issue(s) this PR fixes:

Fixes #318

[jabbate19]

We ball

[hulto]

Prolly need to implement a remove function in the ssh test server.

[codecov]

Codecov Report

Merging #323 (a19927a) into main (4d18ec8) will decrease coverage by 0.19%.
The diff coverage is 70.56%.

@@            Coverage Diff             @@
##             main     #323      +/-   ##
==========================================
- Coverage   74.93%   74.75%   -0.19%     
==========================================
  Files          94       95       +1     
  Lines        6121     6346     +225     
==========================================
+ Hits         4587     4744     +157     
- Misses       1447     1515      +68     
  Partials       87       87              

Files	Coverage Δ
implants/lib/eldritch/src/lib.rs	92.75% <100.00%> (ø)
implants/lib/eldritch/src/pivot/ssh_exec_impl.rs	70.67% <100.00%> (ø)
implants/lib/eldritch/src/pivot.rs	62.58% <94.11%> (+3.80%)	⬆️
implants/lib/eldritch/src/pivot/ssh_copy_impl.rs	67.94% <67.94%> (ø)

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