Vue 3 support

[ardier16]

Vue 3 support

Changed:

• replace vue-template-compiler with @vue/compiler-sfc
• upgrade vue to version 3.0.11
• upgrade demo to Vue 3

@kazupon IMO it should be merged into next branch, and released as next version

Closes #139

[kazupon]

@ardier16
I am very happy to you for your Vue 3 support.
We are planning to release vue-i18n-locale-message v1 first for Vue3 support.
After releasing that, we hope to provide a Vue 3 support version.

I would like you to send me your PR at that time.

[kazupon]

@ardier16
Hi! I've just released v1 for Vue 2
I think I'll release v2 for Vue 3.
Could you resolve the conflict of this PR! 🙏

[ardier16]

@ardier16
Hi! I've just released v1 for Vue 2
I think I'll release v2 for Vue 3.
Could you resolve the conflict of this PR! 🙏

Hi, @kazupon!
Just resolved a conflict, it's ready to be merged.
Is there a next branch for this PR?

[kazupon]

@ardier16
Your PR is OK.
Thank you so much!