Rule Proposal: `valid-v-bind-sync`

[ota-meshi]

Please describe what the rule should do:

This rule checks .sync modifier with v-bind.
Most checking of this rule will do the same check as vue/valid-v-model.

Custom Events .sync Modifier

What category of rule is this? (place an "X" next to just one item)

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

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

<TheComponent v-bind:title.sync="foo + bar" />
<input v-bind:title.sync="foo"/>
<div v-for="todo in todos">
  <TheComponent v-bind:title.sync="todo" />
</div>

Why should this rule be included?

The .sync modifier behaves similarly to v-model, so the same problem may get into it.

I would like to ask your opinion whether this check should be a separate rule or included in valid-v-bind.

[michalsnik]

I think we should create separate rule to check this. And if possible reuse some internal logic between these two :)