feat: add a runtime warning for the old object type transformIndexHtml hook

[sapphi-red]

Description

The old object type transformIndexHtml hook was deprecated in Vite 4. But didn't have a runtime warning.

I considered removing this in Vite 5, but it was still used in many places.

• https://github.com/vbenjs/vite-plugin-html/blob/ac54a6e6c5334ce24454a3b68542114514f632e6/packages/core/src/htmlPlugin.ts#L96-L98
• https://github.com/unocss/unocss/blob/84ad6255bb988946da5555b6dc600dd192bc33fc/packages/vite/src/modes/global/build.ts#L83-L85
• https://github.com/vaadin/flow/blob/76f5fcdeca4c77bf7a74ec6cfbc6882698e98823/flow-server/src/main/resources/vite.generated.ts#L750-L752
• https://github.com/vaadin/flow/blob/76f5fcdeca4c77bf7a74ec6cfbc6882698e98823/flow-server/src/main/resources/vite.generated.ts#L765-L767
• https://github.com/stauren/vise-ssr/blob/87b99834b1711876c89e21472a75979090f2e150/packages/shared/src/vise-scaffold-plugin.ts#L84-L86
• https://github.com/youzan/vant/blob/5accade26567d6b8824a31cce1680f05ae7d37ba/packages/vant-cli/src/config/vite.site.ts#L89-L91
• https://github.com/Borrus-sudo/tinypages/blob/ee6981bdf5dbc049379041e72b0ff0b3a8319db0/packages/vite/src/node/plugins/build/rebuild.ts#L11-L13
• https://github.com/Borrus-sudo/tinypages/blob/ee6981bdf5dbc049379041e72b0ff0b3a8319db0/packages/vite/src/node/plugins/build/rebuild.ts#L34-L36

refs #9669

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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