Implement URL.searchParams and URLSearchParams

[Monti-27]

This Pull Request fixes/closes #4743.

It changes the following:

• adds URLSearchParams and implements URL.searchParams
• keeps URL.searchParams live and cached, including mutation during iteration and forEach()
• re-enables the excluded url-searchparams.any.js WPT case and adds focused runtime tests

Test plan:

• cargo test -p boa_runtime --lib
• cargo test --manifest-path tests/wpt/Cargo.toml url -- --nocapture
• cargo clippy -p boa_runtime --all-features --all-targets -- -D warnings

[Monti-27]

Superseded by #5040, which contains the same change as a single squashed commit.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	49,935	49,935	0
Ignored	2,207	2,207	0
Failed	821	821	0
Panics	0	0	0
Conformance	94.28%	94.28%	0.00%

Tested main commit: d535eee21500b40d2e926d824993439df8eecc4d
Tested PR commit: 4b728c5a09b2d1b91dbb4904b0a505c2253ea594
Compare commits: d535eee...4b728c5