add Request body methods

[Monti-27]

Fixes #5321

This adds the Body methods currently supported by Boa to Request, and tracks body usage so Request cloning and transfer behave correctly.

Tests:

• cargo test -p boa_runtime request -- --nocapture
• cargo make run-ci

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	53,125	53,125	0
Passed	51,049	51,049	0
Ignored	1,482	1,482	0
Failed	594	594	0
Panics	0	0	0
Conformance	96.09%	96.09%	0.00%

Tested main commit: da570fd74bb6cd5b0fc01363451eb710b7ab5a0c
Tested PR commit: 0b5b0044d963624f9a77853ed95d1397441633a6
Compare commits: da570fd...0b5b004

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.74%. Comparing base (6ddc2b4) to head (0b5b004).
⚠️ Report is 954 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5322       +/-   ##
===========================================
+ Coverage   47.24%   59.74%   +12.49%     
===========================================
  Files         476      591      +115     
  Lines       46892    63749    +16857     
===========================================
+ Hits        22154    38084    +15930     
- Misses      24738    25665      +927     

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