Add new 'route-path-style' rule

[bmish]

New rule:

• Title: route-path-style
• Description: Enforces usage of kebab-case (instead of snake_case or camelCase) in route paths.

Kebab-case looks like this URL: https://guides.emberjs.com/release/getting-started/core-concepts/

I'm assuming that kebab-case is the only route path format that we want to promote/enforce in Ember. This format seems to be a best practice / preference across the web, as even Google recommends it:

Consider using punctuation in your URLs. The URL http://www.example.com/green-dress.html is much more useful to us than http://www.example.com/greendress.html. We recommend that you use hyphens (-) instead of underscores (_) in your URLs.

[Turbo87]

@bmish could you extract the changes to the existing rules to separate PRs? those changes make the review of the new rule quite a bit more complicated

[bmish]

@Turbo87 good point, I removed the cleanup of other rules, which should dramatically simplify the PR diff.

[Turbo87]

@bmish I'm wondering if we should make this rule a little more generic. this is definitely a styling rule where different developers may have different opinions and it would be bad to have a separate rule for every style.

I was thinking that maybe we should rename this to route-path-casing (or even route-path-naming) with an optional style option that defaults to kebab case. We might even be able to pass a custom validator function to it to support any custom naming schemes 🤔

I think @rwjblue was a bit skeptical about suggesting that everything should be kebab case but if we make it configurable we might persuade him that this can be a useful rule 😉

[bmish]

@Turbo87 Agreed about making the rule more generic if we are fine with allowing different styles. So I renamed the rule to route-path-style. I'm not sure it's worth adding a configuration yet but we could absolutely do that later if we wanted to add more supported styles.

[Turbo87]

this should be reasonably easy to fix, right? but I guess this is what you meant with "changing the behavior"?

[bmish]

Converting a string to kebab case should be trivial, but yeah, I'd be worried that an autofixer for this rule would go against the following eslint principle, as it could break existing links/URLs:

Avoid any fixes that could change the runtime behavior of code and cause it to stop working.

[Turbo87]

@rwjblue I think this rule, in general, can be useful for some people so I'll go ahead and merge this. I don't think we should turn it on as a recommendation, but having it available for those people that would like to enforce this style (e.g. Square) seems reasonable to me.