fix(expect)!: loosen `toMatchObject` and `objectContaining` for `Proxy.get`

[hi-ogawa]

Description

• closes https://github.com/vitest-dev/vitest/issues/6672

I'm not sure if this behavior is the best, but I'm creating a PR to test a few things. Technically this is a breaking change since people might be using negating expect(someProxy).not.toMatchObject({ ... }) to assert proxy keys not being there.

pros

• convenient for testing Proxy.get
• toMatchObject/objectContaining already allows testing non-enumerable properties (e.g. Error.cause)

cons

• Proxy.get won't give better diff since non-enumerable
• breaking change
• no jest compat

todo

• [ ] docs to explain what type of properties (enumerable vs. non-enumerable) are considered for toEqual, toMatchObject, etc... also diff format

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• [x] It's really useful if your PR references an issue where it is discussed ahead of time. If the feature is substantial or introduces breaking changes without a discussion, PR might be closed.
• [ ] Ideally, include a test that fails without this PR but passes with it.
• [ ] Please, don't make changes to pnpm-lock.yaml unless you introduce a new test example.

Tests

• [ ] Run the tests with pnpm test:ci.

Documentation

• [ ] If you introduce new functionality, document it. You can run documentation with pnpm run docs command.

Changesets

• [x] Changes in changelog are generated from PR name. Please, make sure that it explains your changes in an understandable manner. Please, prefix changeset messages with feat:, fix:, perf:, docs:, or chore:.

[netlify[bot]]

✅ Deploy Preview for vitest-dev ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	f0ca9a31132ef3df3b92e801ff07610ed82212e7
🔍 Latest deploy log	https://app.netlify.com/sites/vitest-dev/deploys/6707487c57cccd0008c90756
😎 Deploy Preview	https://deploy-preview-6675--vitest-dev.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[hi-ogawa]

Closing as par https://github.com/vitest-dev/vitest/issues/6672#issuecomment-2521919672