⚡ improvement(interpolation): enable passage of local components to tag prop

[vhoyer]

This should enable the user to, not only pass global components and html tags, but also locally imported components.

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Of note: I commited this changes directly on github web interface. So I didn't write tests or any lint on commit, I did so because I want to just test the ideia with the community/mantainers, if you like the idea I'm more than willing to fix any mistakes I may have commited.

[kazupon]

Thank you for your PR!

dev branch is reserved for vue-i18n next major dev brach.
8.x branch is maintained for Veu 2.x.
You can check it!

The current specifications of i18n component is here:
https://kazupon.github.io/vue-i18n/api/#i18n-functional-component

In about this PR, We need your more detail explanation and use-case.
Could you tell us about these, please?

[vhoyer]

Yeah sure, I was motivated to do this, because on the company I work for, we have a text component (to standardize text styles between various projects), when this text component is not a global component I can't use it with i18n. Like:

Currently on vue-i18n@8.x I can't do this:

<template>
  <i18n :tag="$options.UiText" path="a.path" />
</template>

<script>
import UiText from 'file'
export default {
  UiText,
}
</script>

This PR makes ⬆️ that example work. A.K.A.: This PR makes i18n be able to render locally imported components instead of only global ones 😄

---

Alternatively, on the current live version, one would have to do the following to achieve the same result:

<template>
  <UiText>
    <i18n :tag="false" path="a.path" />
  </UiText>
</template>

<script>
import UiText from 'file'
export default {
  components: { UiText },
}
</script>

[kazupon]

Thank you for your explanation!
I've understood this feature.

We need unit test for this feature and should change branch to v8.x.

Could you update this PR, please?

[vhoyer]

Sure, will do this later today :D

[codecov-commenter]

Codecov Report

Merging #928 into v8.x will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             v8.x     #928   +/-   ##
=======================================
  Coverage   96.42%   96.42%           
=======================================
  Files          10       10           
  Lines         896      896           
=======================================
  Hits          864      864           
  Misses         32       32           

Impacted Files	Coverage Δ
src/components/interpolation.js	100.00% <ø> (ø)

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[kazupon]

Thanks!
LGTM! 👍