Add Klaus functional test to CI

[breqdev]

Adds the Klaus Dormann 6502 Functional Test as a Rust #[test]. This will run this test in CI.

The test loads the starting address (0x400) and verifies that the program ends up in the success loop.

An extension needed to be made to BlockMemory to accommodate how the Klaus test behaves like a ROM yet requires self-modifying code.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (f1595eb) 19.93% compared to head (cb4c86a) 25.93%.

Files	Patch %	Lines
src/main.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #35      +/-   ##
==========================================
+ Coverage   19.93%   25.93%   +5.99%     
==========================================
  Files          40       40              
  Lines        8714     8731      +17     
==========================================
+ Hits         1737     2264     +527     
+ Misses       6977     6467     -510     

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