Rule Proposal: Disallow properties starting with `:v-`.

[mikegreiling]

Please describe what the rule should do:

I have seen an occasion where a v-if was mistakenly typed as :v-if and the error was not immediately obvious. Since it is unlikely that someone will ever legitimately want to name a property "v-*" we could make a rule to catch these simple typos.

What category should the rule belong to?

• Enforces code style
• Warns about a potential error
• Suggests an alternate way of doing something
• Other (please specify:)

Provide 2-3 code examples that this rule should warn about:

<some-component :v-if="someCondition" />

Additional context

Related issue (on GitLab): https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31222#note_197281204