Rule proposal: `props-names-casing`

[michalsnik]

Style guide:
https://vuejs.org/v2/style-guide/#Prop-name-casing-strongly-recommended

Description:
This rule would enforce proper casing of props in vue components (camelCase).
We already have a rule for checking HTML attributes casing, and this would make a good addition to that rule.

We could add different casing as options and set camelCase as default, but I think we should definitely forbid two of them anyway:

• kebab-case - which doesn't make any sense and should be avoided
• PascalCase - as this is the casing recommended for components, and users should not be able to mix props with components

so in the end there may be two options:

• camelCase
• snake_case

Which makes me think if this rule shouldn't be named props-camel-casing and force only one style of props names.

// bad
props: {
  'greeting-text': String
}

// good
props: {
  greetingText: String
}

[mysticatea]

Could we use just core camelcase rule?

[michalsnik]

Core rule won't work in case someone's using array of props @mysticatea