compiler: Tweak findsymbols caching and add an unsorted mode

[EdCaunt]

Performance upgrades for FindSymbols which yield appreciable compilation time reduction. Mainly based on caching results, although it also introduces an unsorted mode for cases where the check only needs to ensure that a symbol is present.

This is entirely Claude/Codex to begin with so needs review for sanity checking and human readability. I suspect tweaks will be required.

[codecov]

Codecov Report

❌ Patch coverage is 99.15254% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.35%. Comparing base (0164e85) to head (fc8d4d3).

Files with missing lines	Patch %	Lines
tests/test_iet.py	98.83%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3053      +/-   ##
==========================================
+ Coverage   84.26%   84.35%   +0.08%     
==========================================
  Files         258      258              
  Lines       56982    57205     +223     
  Branches     4854     4867      +13     
==========================================
+ Hits        48016    48253     +237     
+ Misses       8139     8126      -13     
+ Partials      827      826       -1     

Flag	Coverage Δ
pytest-gpu-aomp-amdgpuX	68.59% <92.18%> (+0.03%)	⬆️
pytest-gpu-gcc-	79.12% <94.91%> (+0.08%)	⬆️
pytest-gpu-icx-	79.04% <94.91%> (+0.06%)	⬆️
pytest-gpu-nvc-nvidiaX	69.17% <92.18%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.