[cleanup] Refactor Eldritch Library Registration

[KCarretto]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

• adds eldritch_lib!() macro for defining libraries
• Performs related cleanup (remove unused imports, add comments, silence unused args instead of if false)
• Moves each module file to mod.rs to cleanup the eldritch root directory

[codecov]

Codecov Report

Attention: 31 lines in your changes are missing coverage. Please review.

Comparison is base (67970e2) 71.28% compared to head (a66433e) 71.83%.

Files	Patch %	Lines
implants/lib/eldritch/src/sys/mod.rs	57.89%	8 Missing ⚠️
implants/lib/eldritch/src/lib.rs	41.66%	7 Missing ⚠️
implants/lib/eldritch/src/pivot/port_scan_impl.rs	57.14%	3 Missing ⚠️
implants/lib/eldritch/src/process/mod.rs	57.14%	3 Missing ⚠️
implants/lib/eldritch/src/assets/mod.rs	71.42%	2 Missing ⚠️
implants/lib/eldritch/src/file/mod.rs	91.30%	2 Missing ⚠️
implants/lib/eldritch/src/time/mod.rs	66.66%	2 Missing ⚠️
implants/lib/eldritch/src/assets/copy_impl.rs	0.00%	1 Missing ⚠️
implants/lib/eldritch/src/crypto/mod.rs	88.88%	1 Missing ⚠️
implants/lib/eldritch/src/pivot/mod.rs	90.90%	1 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #579      +/-   ##
==========================================
+ Coverage   71.28%   71.83%   +0.54%     
==========================================
  Files         141      142       +1     
  Lines       10092     9955     -137     
==========================================
- Hits         7194     7151      -43     
+ Misses       2732     2638      -94     
  Partials      166      166              

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[hulto]

Some nits otherwise LGTM

[hulto]

We should probably remove this too since it's no longer a good reference.

[Cictrone]

sheeesh