feat(language-core): enhance single root nodes collection

[KazariEX]

This is an enhancement which enabling it to collect all single root nodes under the template branch, and selectively collect single root child node through specific components.

It will also infer the type of $el as the union of all single root nodes.

[pkg-pr-new]

Open in Stackblitz

vue-component-meta

npm i https://pkg.pr.new/vuejs/language-tools/vue-component-meta@4819

vue-component-type-helpers

npm i https://pkg.pr.new/vuejs/language-tools/vue-component-type-helpers@4819

@vue/language-plugin-pug

npm i https://pkg.pr.new/vuejs/language-tools/@vue/language-plugin-pug@4819

@vue/language-server

npm i https://pkg.pr.new/vuejs/language-tools/@vue/language-server@4819

@vue/language-core

npm i https://pkg.pr.new/vuejs/language-tools/@vue/language-core@4819

@vue/language-service

npm i https://pkg.pr.new/vuejs/language-tools/@vue/language-service@4819

vue-tsc

npm i https://pkg.pr.new/vuejs/language-tools/vue-tsc@4819

@vue/typescript-plugin

npm i https://pkg.pr.new/vuejs/language-tools/@vue/typescript-plugin@4819

commit: 649edfb

[KazariEX]

There is an upstream issue I caused that needs to be fixed :)