Set resetMocks to true by default in jest config

[alexkrolick]

• Add resetMocks: true to the template in createJestConfig
• This is a best practice (but not required) for working with RTL tests (Add @testing-library to the default templates #7881)

See also jestjs/jest#9047

[alexkrolick]

I think this would be a breaking change

[kentcdodds]

I agree with this PR. But I wouldn't hold up #7881 for this. You can definitely use React Testing Library without this enabled.

[ianschmitz]

Agreed. I have always set this to true in my jest config of my CRA apps after creation. Populating the jest config in the package.json by default in our bootstrapped apps could accomplish this as a non-breaking change.

I'm for it, let's see what the other maintainers think.

[alexkrolick]

I'm still all for this change