Fixed buffer pool

[proteetpaul]

Add a pool for fixed buffers in io uring. This reduces CPU overhead during IO submission as the buffers don't need to be pinned to memory.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 496 lines in your changes missing coverage. Please review.
✅ Project coverage is 37.86%. Comparing base (cbc679d) to head (a8f4e74).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/common/src/memory/tcache.rs	0.00%	220 Missing ⚠️
src/common/src/memory/pool.rs	0.00%	95 Missing ⚠️
src/common/src/memory/arena.rs	0.00%	87 Missing ⚠️
src/common/src/memory/page.rs	0.00%	55 Missing ⚠️
src/common/src/memory/segment.rs	0.00%	39 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (cbc679d) and HEAD (a8f4e74). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (cbc679d)	HEAD (a8f4e74)
	4	3

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #444       +/-   ##
===========================================
- Coverage   83.59%   37.86%   -45.74%     
===========================================
  Files          78       82        +4     
  Lines       20123    14029     -6094     
  Branches    20123    14029     -6094     
===========================================
- Hits        16822     5312    -11510     
- Misses       2893     8507     +5614     
+ Partials      408      210      -198     

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