Configure vite legacy target

[IlyaSemenov]

Currently, nuxt-bridge injects @vitejs/legacy-plugin without passing it any options:

bridge/src/vite/client.ts

Line 43 in 38036c5

PluginLegacy(),

meaning the target is defaults (whatever it be).

That is incompatible with Nuxt webpack bundler which explicitly sets { ie: 9 } as babel target:
https://github.com/nuxt/nuxt.js/blob/777a4b7f5033c86c37cbd93008f3ca792e4af8bc/packages/babel-preset-app/src/index.js#L96

I propose to use { targets: ['IE 9'] } by default in Vite to keep that behaviour in sync, and also add an option to nuxt config (such as vite.legacy) that will allow user to configure @vitejs/legacy-plugin without using hacks such as I described in #340.