feat(biome_graphql_parser): parse scalar extension

[vohoanglong0107]

Summary

Parse GraphQL scalar extensions (link). This is a small case, as almost all parsing logic was handled by a previous PR focusing on parsing scalar definition.

Test Plan

All tests should pass.

[codspeed-hq]

CodSpeed Performance Report

Merging #2927 will not alter performance

_{Comparing vohoanglong0107:feat-graphql-parse-schema-extension (d24448b) with main (ea0c565)}

Summary

✅ 92 untouched benchmarks