perf: reduce memory usage in profiling

[morrisonlevi]

Description

Utilizes ThinString in the ZendFrame to shrink memory. This shrinks each frame from 7 words to 3 words.

It also moves some label values from Owned to Borrowed, which will save on allocations in the runtime. I played with moving these to ThinString but it doesn't shrink the size of LabelValue (it's so close, I think 1 unused bit away from shrinking down...)

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[pr-commenter]

Benchmarks [ profiler ]

Benchmark execution time: 2025-01-13 20:26:25

Comparing candidate commit e49f49a in PR branch levi/thin-zend-frame with baseline commit b0171fa in branch levi/thin-str.

Found 0 performance improvements and 6 performance regressions! Performance is the same for 23 metrics, 7 unstable metrics.

scenario:walk_stack/1

• 🟥 wall_time [+4.009µs; +4.015µs] or [+32.911%; +32.960%]

scenario:walk_stack/50

• 🟥 wall_time [+3.709µs; +3.720µs] or [+24.354%; +24.431%]

scenario:walk_stack/99

• 🟥 wall_time [+3.866µs; +3.872µs] or [+25.462%; +25.502%]

scenario:walk_stack_instructions/1

• 🟥 instructions [+33.8K instructions; +33.8K instructions] or [+33.379%; +33.382%]

scenario:walk_stack_instructions/50

• 🟥 instructions [+36.8K instructions; +36.8K instructions] or [+35.896%; +35.902%]

scenario:walk_stack_instructions/99

• 🟥 instructions [+37.0K instructions; +37.0K instructions] or [+36.046%; +36.049%]

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.80%. Comparing base (b0171fa) to head (e49f49a).

Additional details and impacted files

@@                 Coverage Diff                 @@
##             levi/thin-str    #2995      +/-   ##
===================================================
+ Coverage            74.78%   74.80%   +0.01%     
  Complexity            2781     2781              
===================================================
  Files                  112      112              
  Lines                11017    11017              
===================================================
+ Hits                  8239     8241       +2     
+ Misses                2778     2776       -2     

Flag	Coverage Δ
tracer-php	74.80% <ø> (+0.01%)	⬆️

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see 1 file with indirect coverage changes

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