[MEDIUM] Pin AJV to fixed releases

[OskarEichler]

Summary

• update AJV 6.x consumers to 6.15.0
• update AJV 8.x consumers to 8.20.0
• add targeted resolutions for the two API Extractor dependencies whose tilde ranges otherwise retain vulnerable AJV 8 minors
• deduplicate the three AJV 8 lockfile entries into one installation

Security impact

AJV versions before 6.14.0 and AJV 8 versions before 8.18.0 are affected by GHSA-2g4f-4pwh-qvx6, a ReDoS when the $data option is enabled. Both installed major lines are moved past their patched versions.

Verification

• yarn install --frozen-lockfile --ignore-scripts
• yarn why ajv confirmed only 6.15.0 and 8.20.0
• yarn audit no longer reports AJV advisories
• yarn lint
• yarn build-types --validate
• JS API tooling: 22 suites, 153 tests, 131 snapshots passed
• git diff --check

[github-actions]

Warning

Missing Test Plan

Please add a "## Test Plan" section to your PR description. A Test Plan lets us know how these changes were tested.

Caution

Missing Changelog

Please add a Changelog to your PR description. See Changelog format