feat: add unit tests from kernel

[kenlig]

This PR integrates some bpf unittests from kernel (https://elixir.bootlin.com/linux/latest/source/tools/testing/selftests/bpf) into bpftime.

These tests from test_maps.c are expected to work:

• test_hashmap
• test_hashmap_sizes
• test_hashmap_percpu
• test_hashmap_walk
• test_arraymap
• test_arraymap_percpu
• test_arraymap_percpu_many_keys
• test_map_large
• test_map_stress
• test_update_delete
• test_map_parallel
• test_map_rdonly
• test_map_wronly_hash

Note hash map tests are only implemented for var_size_hash_map_impl, also used pre-allocated nodes for performance increasing

[codecov]

Codecov Report

Attention: Patch coverage is 96.44860% with 19 lines in your changes missing coverage. Please review.

Project coverage is 92.90%. Comparing base (da6ba42) to head (7361d02).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
runtime/unit-test/maps/kernel_unit_tests.cpp	95.65%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #354      +/-   ##
==========================================
+ Coverage   91.75%   92.90%   +1.14%     
==========================================
  Files          34       37       +3     
  Lines        1189     1720     +531     
  Branches       61      103      +42     
==========================================
+ Hits         1091     1598     +507     
- Misses         98      122      +24     

Flag	Coverage Δ
attach tests (uprobe & syscall trace)	97.30% <ø> (-0.05%)	⬇️
runtime tests	91.15% <96.44%> (+2.57%)	⬆️

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