New: Add vue/require-shorthand-boolean-prop rule

[inker]

This PR adds the vue/require-shorthand-boolean-prop rule.

ref #775

[ota-meshi]

Thank you for this PR.

Due to the props definition of the used component, :isValid="true" and isValid are not equivalent.
I don't think this rule can report errors correctly.

What do you think?

[inker]

Due to the props definition of the used component, :isValid="true" and isValid are not equivalent.

I see what you mean. Currently, it only works for boolean props. Will investigate if it's possible to do prop type checking.

[ota-meshi]

I don't think there is a good way to do type checking right now, so I'll close this PR. If you know a good way, please let me know.