fix(language-service): handle internal item key with leading slash correctly

[KazariEX]

partial-fix #4893

[pkg-pr-new]

Open in Stackblitz

vue-component-meta

pnpm add https://pkg.pr.new/vuejs/language-tools/vue-component-meta@4894

vue-component-type-helpers

pnpm add https://pkg.pr.new/vuejs/language-tools/vue-component-type-helpers@4894

@vue/language-core

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-core@4894

@vue/language-plugin-pug

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-plugin-pug@4894

@vue/language-service

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-service@4894

@vue/language-server

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/language-server@4894

vue-tsc

pnpm add https://pkg.pr.new/vuejs/language-tools/vue-tsc@4894

@vue/typescript-plugin

pnpm add https://pkg.pr.new/vuejs/language-tools/@vue/typescript-plugin@4894

commit: 8b01d8c