perf: creating `HeaderMap` from iterator

[shashitnak]

Summary:
Briefly describe the changes made in this PR.

Issue Reference(s):
Fixes #... (Replace "..." with the issue number)

Build & Testing:

• [ ] I ran cargo test successfully.
• [ ] I have run ./lint.sh --mode=fix to fix all linting issues raised by ./lint.sh --mode=check.

Checklist:

• [ ] I have added relevant unit & integration tests.
• [ ] I have updated the documentation accordingly.
• [ ] I have performed a self-review of my code.
• [ ] PR follows the naming convention of <type>(<optional scope>): <title>

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.74%. Comparing base (186fd6b) to head (2d3c8cd). Report is 25 commits behind head on perf/base.

:exclamation: Current head 2d3c8cd differs from pull request most recent head 5e5cdbf

Please upload reports for the commit 5e5cdbf to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           perf/base    #1938   +/-   ##
==========================================
  Coverage      89.73%   89.74%           
==========================================
  Files            155      155           
  Lines          15837    15842    +5     
==========================================
+ Hits           14212    14217    +5     
  Misses          1625     1625           

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[github-actions[bot]]

Bencher

Report	Mon, May 13, 2024 at 16:56:41 UTC
Project	tailcall
Branch	1938/merge
Testbed	benchmarking-runner

🚨 1 ALERT: Threshold Boundary Limit exceeded!

Benchmark	Measure (units)	View	Value	Lower Boundary	Upper Boundary
input/vars.missing	Latency (nanoseconds (ns))	🚨 (view plot | view alert)	11.55 (+41.07%)		9.52 (121.32%)

Click to view all benchmark results

Benchmark	Latency	Latency Results nanoseconds (ns) | (Δ%)	Latency Upper Boundary nanoseconds (ns) | (%)
group_by	✅ (view plot)	548.07 (-9.52%)	638.10 (85.89%)
input/args.missing	✅ (view plot)	22.80 (-8.76%)	27.16 (83.94%)
input/args.nested.existing	✅ (view plot)	41.83 (-21.70%)	65.70 (63.67%)
input/args.nested.missing	✅ (view plot)	38.15 (-1.33%)	40.71 (93.71%)
input/args.root	✅ (view plot)	38.19 (-23.71%)	61.91 (61.69%)
input/headers.existing	✅ (view plot)	33.01 (+3.83%)	33.36 (98.97%)
input/headers.missing	✅ (view plot)	31.57 (+2.81%)	32.83 (96.19%)
input/value.missing	✅ (view plot)	23.48 (-0.34%)	25.28 (92.92%)
input/value.nested.existing	✅ (view plot)	41.94 (+1.27%)	43.58 (96.24%)
input/value.nested.missing	✅ (view plot)	37.09 (+2.13%)	38.24 (97.00%)
input/value.root	✅ (view plot)	37.81 (-2.15%)	40.02 (94.49%)
input/vars.existing	✅ (view plot)	7.43 (-9.94%)	9.02 (82.42%)
input/vars.missing	🚨 (view plot | view alert)	11.55 (+41.07%)	9.52 (121.32%)
test_batched_body	✅ (view plot)	2,630.90 (-99.73%)	2,757,085.92 (0.10%)
test_batched_body #2	✅ (view plot)	1,709,200.00 (-2.91%)	1,891,165.02 (90.38%)
test_data_loader	✅ (view plot)	475,530.00 (+0.43%)	490,400.93 (96.97%)
test_handle_request	✅ (view plot)	168,690.00 (-2.14%)	181,997.06 (92.69%)
with_mustache_expressions	✅ (view plot)	1,115.50 (-4.96%)	1,238.14 (90.09%)
with_mustache_literal	✅ (view plot)	141.43 (-80.33%)	833.32 (16.97%)

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[github-actions[bot]]

Action required: PR inactive for 2 days. Status update or closure in 5 days.

[github-actions[bot]]

Action required: PR inactive for 2 days. Status update or closure in 5 days.

[amitksingh1490]

No improvement