The types used in the ApprovalController tests for sinon tests were
wrong. `typeof sinon.spy` was being used to get the spy type, but this
returns the type of the `spy()` function, not of a spy instance.

Instead the type `SinonSpy` is used instead. This type is provided by
the `@types/sinon` package. For some reason it seems to provide more
correct type information than `ReturnType<typeof sinon['spy']>`, though
I'm not sure why.

The sinon import was updated to use `import` rather than `require` as
well, as TypeScript seemingly doesn't type anything that is imported
using `require`.

This introduced two new type errors caused by us using private methods
in the test. I've silenced these errors for now by casting to `any`,
but we should update these tests later to stop relying upon internals.

The types used in the ApprovalController tests for sinon tests were
wrong. `typeof sinon.spy` was being used to get the spy type, but this
returns the type of the `spy()` function, not of a spy instance.

Instead the type `SinonSpy` is used instead. This type is provided by
the `@types/sinon` package. For some reason it seems to provide more
correct type information than `ReturnType<typeof sinon['spy']>`, though
I'm not sure why.

The sinon import was updated to use `import` rather than `require` as
well, as TypeScript seemingly doesn't type anything that is imported
using `require`.

This introduced two new type errors caused by us using private methods
in the test. I've silenced these errors for now by casting to `any`,
but we should update these tests later to stop relying upon internals.

Moved the compatibility test into it's own workflow. 

This implements the change described here
MetaMask/metamask-module-template#269,
ensuring that the compatibility test continues to provide value in
identifying issues, but does not hold up individual PRs that do not
introduce these issues.

This is the release for version 17.1.0.

```
4e74bb9 feat: add RPC methods described in (revised) EIP-7715 (#396)
0a66477 Run compatibility test only in main branch. (#397)
```

---------

Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Jeff Smale <6363749+jeffsmale90@users.noreply.github.com>
Co-authored-by: Elliot Winkler <elliot.winkler@gmail.com>