Proposal: Upgrade echarts-examples to Vue 3

[KapilSachdev]

Hi Apache Echarts Team,

I am planning to upgrade the repository from Vue 2 to Vue 3.

I've already started the migration and have some initial changes documented in PR #124.

Before I dedicate further time to this effort, I wanted to confirm if the team is open to accepting a PR that completes this Vue 3 upgrade.

[KapilSachdev]

I went ahead and completed the migration as there were not many Vue components.