Add no-unnecessary-waiting rule

[SaladFork]

Based on the best practice and what I think was originally suggested in #4. Will error if calling cy.get with a number literal. Also adds this rule to the default recommended set of this plugin.

Based on #6, will refactor/rebase if any changes are needed there. I can also move the base stuff (set up a recommended config, test tools, etc.) to its own PR if it would be easier.

---

Example:

// cypress/.eslintrc.js
module.exports = {
  plugins: ['cypress'],
  extends: 'plugin:cypress/recommended',
  env: {
    'cypress/globals': true
  }
}

// cypress/test.js
describe('something', () => {
  it('might do a thing', () => {
    cy.visit('/');
    cy.wait(1000);
  });
});

$ yarn run eslint cypress/test.js

./cypress/test.js
  4:5  error  Do not wait for arbitrary time periods  cypress/no-unnecessary-waiting

✖ 1 problem (1 error, 0 warnings)

[chrisbreiding]

Looks good. Thanks a lot! I'll merge the other one first after the minor change is made and then merge this one.

[chrisbreiding]

Released in v2.1.0 🎉