LegacyHandler in 4.12 providing frozen options to Adapters

[kiosion]

Reproduction

I've put up a PR with a failing test case, and what I think could work as a fix - #8576

Description

In 4.12, the options LegacyHandler passes on to Adapters from requests are frozen, making attempts to modify them within query/queryRecord/urlForQuery/etc methods throw TypeErrors. Ideally, these would still be mutable, as they were in previous releases of ember-data.

Versions

├─ @ember-data/adapter@4.12.0
├─ @ember-data/canary-features@4.11.3
├─ @ember-data/debug@4.12.0
├─ @ember-data/graph@4.12.0
├─ @ember-data/json-api@4.12.0
├─ @ember-data/legacy-compat@4.12.0
├─ @ember-data/model@4.12.0
├─ @ember-data/private-build-infra@4.12.0
├─ @ember-data/record-data@4.11.3
│  └─ @ember-data/private-build-infra@4.11.3
├─ @ember-data/request@4.12.0
├─ @ember-data/rfc395-data@0.0.4
├─ @ember-data/serializer@4.12.0
├─ @ember-data/store@4.12.0
├─ @ember-data/tracking@4.12.0
└─ ember-data@4.12.0