chore(vscode): use unjs/unbuild for bundling

[KermanX]

Use https://github.com/unjs/unbuild to bundle the VSCode extension, also as a preparation for #4994.

Notes:

• To dev the extension: run pnpm dev:vue, the command will exit after the stub files generated (no need to watch file changes), then F5.
• To build the extension: like before.
• Other packages except the VSCode extension remain unchanged.
• Using sonda for package size reporting.

TODOs:

• Should the tasks defined in .vscode/tasks.json and .vscode/launch.json be restored?
• What is node_modules/vue-typescript-plugin-pack/ used for?

[pkg-pr-new]

Open in Stackblitz

vue-component-meta

pnpm add https://pkg.pr.new/vuejs/language-tools/vue-component-meta@4998

vue-component-type-helpers

pnpm add https://pkg.pr.new/vuejs/language-tools/vue-component-type-helpers@4998

@vue/language-plugin-pug

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-plugin-pug@4998

@vue/language-core

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-core@4998

@vue/language-server

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-server@4998

@vue/language-service

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-service@4998

vue-tsc

pnpm add https://pkg.pr.new/vuejs/language-tools/vue-tsc@4998

@vue/typescript-plugin

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/typescript-plugin@4998

commit: 13daf63

[sxzz]

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