Add ELF loader

[Schamper]

A very rudimentary ELF loader that can (currently) load and execute statically compiled ELF files.

The loader is very rough so the process will segfault as soon as it's done executing.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 192 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.45%. Comparing base (a4a7b6b) to head (3b7993f).

Files with missing lines	Patch %	Lines
dissect/executable/elf/tools/loader.py	0.00%	192 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #37      +/-   ##
==========================================
- Coverage   81.92%   73.45%   -8.48%     
==========================================
  Files          24       25       +1     
  Lines        1665     1857     +192     
==========================================
  Hits         1364     1364              
- Misses        301      493     +192     

Flag	Coverage Δ
unittests	73.45% <0.00%> (-8.48%)	⬇️

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