feat(proxy): add http and grpc proxy

[karatakis]

Summary:
allow proxy setting for @httpand @grpc directives

Issue Reference(s):
Fixes #2820

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]

Codecov Report

Attention: Patch coverage is 94.08284% with 10 lines in your changes missing coverage. Please review.

Project coverage is 87.16%. Comparing base (090b8b0) to head (9e401c9).
Report is 81 commits behind head on main.

Files with missing lines	Patch %	Lines
src/core/app_context.rs	68.75%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2875      +/-   ##
==========================================
- Coverage   87.30%   87.16%   -0.15%     
==========================================
  Files         254      253       -1     
  Lines       25311    25668     +357     
==========================================
+ Hits        22099    22374     +275     
- Misses       3212     3294      +82     

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[github-actions]

Bencher Report

Branch	2875/merge
Testbed	benchmarking-runner

Click to view all benchmark results

Benchmark	Latency	Benchmark Result nanoseconds (ns) (Result Δ%)	Upper Boundary nanoseconds (ns) (Limit %)
from_json_bench	📈 view plot 🚷 view threshold	6,297,600.00 (+1.91%)	6,310,842.12 (99.79%)
group_by	📈 view plot 🚷 view threshold	478.98 (-2.26%)	513.99 (93.19%)
input/args.missing	📈 view plot 🚷 view threshold	25.88 (+0.93%)	27.74 (93.28%)
input/args.nested.existing	📈 view plot 🚷 view threshold	46.03 (+1.19%)	48.33 (95.25%)
input/args.nested.missing	📈 view plot 🚷 view threshold	38.66 (-0.08%)	40.87 (94.60%)
input/args.root	📈 view plot 🚷 view threshold	43.17 (+4.34%)	45.05 (95.83%)
input/headers.existing	📈 view plot 🚷 view threshold	33.01 (+4.54%)	34.09 (96.85%)
input/headers.missing	📈 view plot 🚷 view threshold	31.84 (+3.89%)	33.45 (95.19%)
input/value.missing	📈 view plot 🚷 view threshold	23.42 (+0.13%)	24.68 (94.90%)
input/value.nested.existing	📈 view plot 🚷 view threshold	42.92 (-0.43%)	45.77 (93.77%)
input/value.nested.missing	📈 view plot 🚷 view threshold	36.82 (+0.51%)	38.55 (95.50%)
input/value.root	📈 view plot 🚷 view threshold	41.22 (+6.48%)	41.65 (98.97%)
input/vars.existing	📈 view plot 🚷 view threshold	8.44 (+1.61%)	9.55 (88.40%)
input/vars.missing	📈 view plot 🚷 view threshold	8.88 (-1.27%)	11.77 (75.44%)
synth_nested	📈 view plot 🚷 view threshold	138,110.00 (+23.36%)	174,540.98 (79.13%)
synth_nested_borrow	📈 view plot 🚷 view threshold	80,107.00 (+55.70%)	102,872.58 (77.87%)
test_batched_body	📈 view plot 🚷 view threshold	1,893.70 (-2.50%)	2,079.66 (91.06%)
test_batched_body #2	📈 view plot 🚷 view threshold	1,517,600.00 (-4.09%)	1,728,414.67 (87.80%)
test_data_loader	📈 view plot 🚷 view threshold	404,020.00 (-1.03%)	458,138.25 (88.19%)
test_handle_request	📈 view plot 🚷 view threshold	131,110.00 (-5.88%)	149,986.10 (87.41%)
test_handle_request_jit	📈 view plot 🚷 view threshold	96,653.00 (-13.01%)	149,579.85 (64.62%)
test_http_execute_method	📈 view plot 🚷 view threshold	14,610.00 (+1.73%)	14,885.95 (98.15%)
with_mustache_expressions	📈 view plot 🚷 view threshold	1,102.10 (-0.74%)	1,177.99 (93.56%)
with_mustache_literal	📈 view plot 🚷 view threshold	699.25 (-1.73%)	763.35 (91.60%)

🐰 View full continuous benchmarking report in Bencher

[github-actions]

Action required: PR inactive for 5 days.
Status update or closure in 10 days.

[github-actions]

PR closed after 10 days of inactivity.