Fix REST client query param serialization

[JedimEmO]

Summary

• serialize generated REST client query params through the reqwest serde-backed query path instead of to_string()
• emit repeated query keys for Vec and Option<Vec> query params
• add e2e coverage for Vec query params and serde-renamed enum query params without Display
• bump ras-rest-macro from 0.1.1 to 0.2.0 and add the Unreleased changelog entry

Fixes #3.

Verification

• cargo test -p ras-rest-macro --all-features
• cargo test -p ras-rest-macro --test e2e
• cargo test -p ras-rest-macro --test http_integration
• cargo check -p ras-rest-macro --all-features
• cargo clippy -p ras-rest-macro --all-features --tests -- -D warnings
• npm --prefix tests/playwright test